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7th Sep 2016 20:22 BSTRolf Luetcke Expert



I have always liked pseudomorphs and today I came across a neat one and thought it might be nice to start a thread of pseudomorphs many of you have come across.

This one is a chrysocolla after cuprite. The habit of the cuprite is easy to see. On another part of the specimen is the actual cuprite still before it is replaced.

Hope people find this a fun thread.

7th Sep 2016 22:20 BSTTony Albini

Rolf, on page 10 or 11 of my Mindat photos, you can see two "wolframite", actually Ferberite pseudomorphs after Scheelite from Trumbull, CT

8th Sep 2016 02:51 BSTAntonio Nazario


Calcite replacing a shell from the fort drum crystal mine, Florida

8th Sep 2016 03:21 BSTAlfredo Petrov Manager

Opal replacing snail, from Gifu, Japan:

8th Sep 2016 04:13 BSTDoug Schonewald

Chalcedony replacing snail shells.

8th Sep 2016 09:17 BSTChris Rayburn

Hematite after siderite, Lake George area, Teller County, Colorado. 8 cm x 5.5 cm.

8th Sep 2016 12:32 BSTReiner Mielke Expert Skutterudite after? Anyone have any ideas on what it might be after?

8th Sep 2016 13:37 BSTRolf Luetcke Expert


This one is from St. David, Arizona, a calcite pseudomorph after gypsum. Found these in only one tiny area a half mile from our house.

8th Sep 2016 15:38 BSTSteve Hardinger Expert

How about a very common pseudomorph example: a mineral replaces money?

8th Sep 2016 16:31 BSTD. Peck

Are not the first three fossils rather than pseudomorphs?

8th Sep 2016 18:31 BSTZach Berghorst

Pseudomorphs are always a favorite of mine. My favorite specimen I own: Malachite pseudo. Cuprite from Emke Mine, Namibia

Size: 2 x 1.25 x 1 inches


8th Sep 2016 20:20 BSTVik Vanrusselt Expert

"Explaining" or "naming" pseudomorphs in English seems to be quite easy: mineral Y after mineral X (as in: it used to be mineral X, but it is now completely replaced by mineral Y).

However, when you turn to German, it becomes: Mineral Y nach Mineral X.

The word "nach" can mean both "after" and "to" in German.

In some cases it's fairly easy to understand which one of the meanings it should be (e.g. with the pictured "chrysocolla after cuprite", since cuprite is never bluish green (or greenish blue?)).

But I guess there could be cases where the meaning of "nach" is not so clear?

Same goes for Dutch (which is derived from German), we translate the German "nach" to either "after" or "to" as well.

Any thoughts?


8th Sep 2016 20:40 BSTErik Vercammen Expert

Donald, a lot of fossils are pseudomorphs: calcite replacing aragonite, pyrite instead of calcite, quartz replacements etc.

8th Sep 2016 20:46 BSTPeter Slootweg

It seems to be matter of taste what defines a pseudomorph. The malachite on cuprite is not really a pseudomrph but rather an overgrowth of one mineral over another. I believe the same goes for the chrysocolla on cuprite. I would not call these pseudomorphs. The hematite that has replaced the siderite is a true pseudomrph since it has replaced most of the former mineral although it may still contain a core of unaltered material or may be hollow. The replacement has occurred inside the boundaries of the former mineral and the replacing mineral is made up of many individuals instead of one big crystal lattice. Therefore, as Rock Currier pointed out, there would not be such a thing as a transparent pseudomorph. Fossils are pseudomorphs after once living organisms. I think the term pseudomorphs should be reserved for "fossilized" minerals. An epimorph would be a coating on a mineral that dissolved, leaving the coating behind ,that would still show the outlines of the mineral it grew on. I'm curious how other collectors look at the subject.


8th Sep 2016 20:48 BSTPavel Kartashov Manager

Many years ago I sold natrojarosite pseudomorphose after fir cones from Kunashir island. Unfortunately no photodocumentation was preserved.

These are very complex pseudomorphoses after new (high Y-REE, niobian, Mn-free, F-dominant?) eudialyte group member:, - more than 12 mineralsforms this aggregate.



8th Sep 2016 21:06 BSTRichard Gunter Expert

Hi Pavel:

Mont Saint Hilaire has a number of similar psudomorphs after Eudialyte including:

8th Sep 2016 21:43 BSTAlfred L. Ostrander

I think Don brought up a valid point. I just checked 10 dictionarie/encyclopedias for the definition of a pseudomorph. Maybe this is a European thing because only the Encyclopaedia Brittanica allude to petrified wood as a pseudomorph. Then I checked petrifaction. No referral to psuedomorphing. So here is what I covered.

Pseudomorph: A crystal consisting of one mineral but having the form of another which it has replaced.

Petrifaction: The process by which organic material is converted into a fossil through the replacement of the organic material or the filling of the original spaces with minerals.

Only one source indicated petrifaction (preferred over petrification) as a pseudomorph but mentioned nothing about a mineral replacing a mineral as the definition I presented seems to indicate. Petrifaction in all other sources indicated that a replacement, not a chemical conversion occoured.

There are those cases where aragonite in original shell preservation has altered to calcite. As to pyrite replacing aragonite/calcite, the removal of the calcite and the subsequent infilling of the void by pyrite appears to be the more common process. How do you convert calcite, a calcium carbonate, to pyrite, an iron sulfide by a chemical process like what happens when pyrite, an iron sulfide is chemically converted to hematite, an iron oxide.

I believe the defining points are the conversion of a chemical compound to another chemical compound creating a pseudomorph and the replacing of an organic compound that once filled a space in the rock to a fossil. The problem is the confusing usage of the word replacement in both definitions. Replacement of pyrite isn't exactly the same as removal of organic compounds and infilling of the consequent void by the process of petrifaction.

I can say from collecting experience that the calcite filling the voids in fossil clams (Mercenaria) is not a pseudomorph or generally a replacement of the actual shell. I believe the shells are old enough that the aragonite structure of the original shell has probably shifted to calcite.

I doubt I cleared much up here but I am sticking with the best definitions I can come up with, not just my own opinion. And I can not recall a single time any of the palentologists I have been around or worked with called petrified wood a pseudomorph. The called it replaced or petrified. So help me out here if I am really missing something. And I hope to get replies better than there is an exception to every rule or mother nature is messy.

Best Regards,

Al O

8th Sep 2016 21:45 BSTBob Harman

I have pictured, on the Midwest Sedimentary Geode thread, a number of these so-called Indiana geodized fossils where quartz replaces the mid mississippian age invertebrate organism forming either a solid or hollow geode. Here is one example of a brachiopod replaced by quartz. The interior is hollow with smoky quartz crystals.

I have never considered these as a type of pseudomorph, agreeing with DON. Should I now consider these a type of pseudomorph or is DON correct? CHEERS.....BOB


8th Sep 2016 21:47 BSTPavel Kartashov Manager

Hi Richard!

In any alkaline massif where presents early eudialyte group minerals you will find pseudomorphoses after them, formed during hydrothermal alteration connected with decreasing (or more rarely increasing) of alcalinity of solutions.

But I never observed so complex pseudomorphoses after eudialyte as in HBU pagmatites.

For example these apoEud PS from Mt. Malosa completely consists of quartz and zircon - all other constituents were leached out.



Here we can to see eudialyte grain almost completely eaten by zirsinalite (increasing of alcalinity), which itself is transforming into lovozerite (decreasing of alcalinity) right now with formation of white films of thermonatrite.

Here you can to see how eudialyte was replaced by white terskite crusts (decreasing of alcalinity).

But where besides Khaldzan did you saw 12 different minerals together replacing eudialyte crystal?

8th Sep 2016 22:11 BSTPavel Kartashov Manager

This is another example of pseudomorphose from Mt. Malosa - Here muscovite replaced probably milarite xl.

This sample of pseudomorphose also is from Mt. Malosa pegmatites


Here we see classical classic - epitaxtial intergrowth of two crystals of different REE-fluorcarbonates (apparently bastnasite-(Ce) and synchysite-(Ce)) which is completely shilded by outer crust of monazite-(Ce). Dense grey crust of monazite completely cover whole the intergrowth and didn't allow me to analyze composition of initial carbonates without damage of the specimen (by the way priced 600$).

8th Sep 2016 22:16 BSTAlfred L. Ostrander


I would have to agree with you and call it petrifaction, a physical replacement of calcite by quartz. A chemical process would be involved in breaking down the calcite and the chemistry of silica in solution and its deposition in the voids left by the calcite as it was removed. And the original calcium structure of the fossil would be organic in origin.

Best Regards,

Al O

8th Sep 2016 22:17 BSTPavel Kartashov Manager

This is completely different sort of pseudomorphoses.:-D

8th Sep 2016 22:23 BSTAlfred L. Ostrander


Could you explain what you mean by calling it a completely different source of pseudomorphoses?

8th Sep 2016 22:39 BSTPavel Kartashov Manager

Not source, but sort. Completely mineralized manmade objects.

The intermediate type of psudomorphoses are manmade transformation of natural objects. For example, if somebody will heat diamond crystal in vacuum, finally he will obtain pseudomorphose of graphite after diamond.

I don't know, how to appreciate such facts as this - this crystal of borax died on my hands. On the photo you can to see initial stage of its pseudomorphisation, now it is completely replaced by tincalconite.

All this is good, but I again remain without borax in my collection...:-(:-(:-( I myself killed this borax crystal, I was should to store it in freezer.

8th Sep 2016 22:47 BSTChris Rayburn

At the risk of hogging the thread here's a nice example of "uralite;" i.e., actinolite after diopside, from the Calumet Iron Mine, Chaffee County, Colorado. 8.5 cm x 5.5 cm; largest crystal is 4.5 cm. Like Zach, I'm a big fan of pseudomorphs, and we have some good ones here in CO.

8th Sep 2016 23:04 BSTRichard Gunter Expert

Hi Pavel:

The MSH pseudomorphs after Eudialyte are usually much simpler. Normally the Eudialyte pseudomorphs are only Catapleiite; this sample was unusual because it has 2 phases. I do not know whether the Manganneptunite crystals are part of the pseudomorphing process but they seem to always be present as crystals on the surface of these samples. I guess that is where the Mn goes. No Fe to form Ferriallanite. As far as I know they are complete pseudomorphs. My sample has a broken pseudomorph on it with no Eudialyte left in the core; it has all been converted to Gaidonnayite.

8th Sep 2016 23:10 BSTScott Rider

Just to clear my own mind here, here is what I can remember; but are there any other types?

Pseudomorph -- one mineral replacing another mineral, that retains the original shape (or as close as possible) of the first mineral. Can be more than one pseudo (eg. chrysocolla after malachite after azurite from Congo).

Epimorph -- type of pseudo where a mineral coats or replaces parts of one mineral and that original mineral is dissolved away.

Paramorph -- a mineral formed by the conversion of one crystalline form polymorph into another. Like the different types of quartz...


8th Sep 2016 23:38 BSTPavel Kartashov Manager

Epimorphoses don't directly connected with pseudomorphism, because the later mineral filling cavity, empty space after dissolution of the former mineral. Epimorphoses of betpakdalite-(CaCa) after pyrite crystals are very abundant (besides type specimens betpakdalite, of course, not in natureat all). Here powdery masses of betpacdalite filled empty space after pyrite dissolution.

Paramorphoses of beta-quartz after alpha-quartz crystals or acanthite after argentite crystals are special cases of pseudomorphism and are pseudomorphoses on more the higher level, being paramorphoses on more the lower one.

8th Sep 2016 23:50 BSTPavel Kartashov Manager

Yes Richard,

very often eudialyte replaced only by sole catapleiite with formation of empty space instead of removed substances - Ancylite and chabasite here are typicaly epimorhic.

Formation of empty space is typical process connected with loss of matter during pseudomorphism - Initially the rock looks like this -

9th Sep 2016 00:04 BSTBob Harman

I now believe that the three examples of minerals replacing organisms posted earlier, including mine should not be considered pseudomorphs.

Mine was quartz replacing an invertebrate shell (aragonite) and forming a rock structure known as a (quartz) geode. The other 2 examples were of calcite replacing the shell, the hard parts (also probably aragonite) of an invertebrate organism, and forming a fossil. Just as if silica were to replace a dinosaur bone, it would then be considered a fossil. In the classic definition, none of these would be considered a pseudomorph. My opinion. CHEERS.......BOB

9th Sep 2016 00:05 BSTRichard Gunter Expert

Hi Pavel:

Your first photograph looks, on a much larger scale, like the outer edge of the MSH pseudomorph. The Gaidonnayite is more granular.

9th Sep 2016 01:10 BSTRolf Luetcke Expert


You mentioned that the chrysocolla was coating the cuprite! Sorry, it is completely replaced and the chrysocolla in places is translucent when the lighting is right, so a true pseudomorph. I am aware of the concept of which you spoke but this is a complete replacement, that is why I liked it so much.

I see one mineral coating another often and know those are not true pseudomorphs. This one is.


Here are another two true pseudomorphs that are well known.

9th Sep 2016 01:34 BSTDoug Schonewald

Consensus on this was Limonite after Dolomite

9th Sep 2016 01:49 BSTRolf Luetcke Expert


Loved your muscovite after milarite. Great photo. Others have put in nice ones also, kind of what I was hoping to see.

I have tried to find a chart of some kind or a listing of the pseudomorphs that are known but that is asking a lot. I have made a list of ones we have and it is quite a long list.

9th Sep 2016 02:26 BSTJim Robison

Lots of good examples shown. Tsumeb alone has many (over fifty I believe at last count). It is easy to see why some collectors specialize in this type of mineral occurrence.

The one sure way to get a variety of opinions is to try to rigorously define what the word pseudomorph means. Someplace in my files is a fascinating many page article by Si Frazier tracing the history of the word, and its variants over time including old German and other sources. More recently John White, another mineralogist for whom I also have great respect, tackled the topic. The use of the word seems to vary with time, background, and a wide range of other factors. I can practically guarantee that no matter how much we discuss it there will never be agreement on all aspects. White's articles in Rocks and Minerals do very well for current definitions, but even there reasonable people may disagree in parts. Mal Southwood and I ran head on into the topic of epimorph meanings preparing our recent Tsumeb dolomite cast article. For our purposes, we took a slightly different track than White does.

What is abundantly clear is that however we try to describe them, they are fascinating objects to consider and admire.

9th Sep 2016 06:01 BSTAlfredo Petrov Manager

"Pseudomorph" just means false shape. So an old shoe replaced by gypsum, or a dead body replaced by copper are, logically, pseudomorphs. The dead miner doesn't have the shape of a copper crystal. You cannot arbitrarily decide that the meaning of a word only applies to the class of stuff you're interested in. I told my daughter that rap wasn't really music, and she quite emphatically disabused me of my restrictive notion. :-D

9th Sep 2016 07:05 BSTDon Windeler

Great topic and one that's fueled my second largest subcollection behind native copper. I love me my replacements, for sure.

A previous poster mentioned the article by the Fraziers, published back in 2004. That's still my favorite reference on the topic and one I'd flagged in another post. For those interested, here's the link: Pseudomorphs: An Introduction. You'll need to scroll down a bit past the meeting notes.

Not everyone will agree with the full suite of examples they discuss that could be (or have been) considered pseudomorphs. I like it because it gives a pretty comprehensive view in an easy to read format.

As for actual pseudos, I'll stick in this example of phlogopite partially replaced by lazurite from Sar-e-sang in Afghanistan. Not my picture (copyright Rob Lavinsky) but in my collection for the past couple of years.



9th Sep 2016 08:21 BSTErik Vercammen Expert

See Extra Lapis 43 Pseudomorphosen (in German)

9th Sep 2016 13:47 BSTReiner Mielke Expert

""Pseudomorph" just means false shape" I agree with Alfredo. So is this a pseudomorph? Limestone after hamburger.

9th Sep 2016 13:49 BSTRolf Luetcke Expert




Great read of Si Fraziers talk and it gives a great amount of information.

The two here I found at a small unnamed prospect in the Chiricahua Mts. in SE Arizona. They are both pseudomorphs after tetrahedrite. The first one is of the rometite variety cuproromeite that has completely replaced the tetrahedrite and has a coating of azurite.

The second is of the tetrahedrite faithfully replaced by the romeite group, oxyplumboromite.

This small prospect has a lot of replacements going on. These two were tiny but very interesting.

9th Sep 2016 13:49 BSTDale Foster Expert


Classic replacement of feldspar crystals by Cassiterite from Wheal Coates, St Agnes.

9th Sep 2016 13:53 BSTDale Foster Expert


Pseudomorphs of Wolframite after Scheelite from Cligga Mine, not easy to photograph well.

9th Sep 2016 13:55 BSTRolf Luetcke Expert


Great hamburger!!!

9th Sep 2016 14:37 BSTPavel Kartashov Manager

Dear Rolf,

I saw rotten fahlores from may be hundred deposits, but never observed formation of plumboromeite after it.

Some sulphosalts and sulphides easily are replaced by plumboromeite (e.g. boulangerite) but never tetrahedrite or tennantite. Lead is enough low mobile in oxidation zone in most cases.

9th Sep 2016 15:40 BSTDan Costian


Your idea of this trend is great; I am also a pseudomorphs lover.

Here is a recent acquisition: malachite after azurite from Liufengshan Mine, Guichi District, Chizhou Prefecture, Anhui Province, China.


9th Sep 2016 15:53 BSTAlfredo Petrov Manager

No, Reiner, not a pseudomorph, because it's not a wrong shape for limestone, which can be any shape. (Yes, I know you're only joking) :-D

Great rock. I'd collect something like that. I have a rock that looks like a shoe.

9th Sep 2016 16:07 BSTAlfred L. Ostrander

I am thoroughly enjoying all the photos of various pseudomorphs. However, should the the topic of what a pseudomorph really is by definition be seperated out. I have heard a lot of opinion and had read Si Frazier's overview of the history of the term and changes in meanings before I posted my original comments. So I think it can be said that the meanings of the word have morphed through time.

I can't say I live or die by strict scientific definitions but it is very useful when trying to communicate concepts to have solid working definitions. Alfredo correctly noted that pseudomorph literally translates as false form. But by that logic crystal comes from the Greek krustallos or sometimes expressed krystallos that means icy cold. So are all our crystals icy cold or should anything icy cold be called a crystal? And we certainly don't believe that quartz is water that froze so cold it can't melt. I am uncomfortable that the term can be used so broadly, almost glibly, just as pseudo-octahedron or whatever crystal pseudo form is the latest pop word also gets tossed about so easily. I almost feel like a lot of pseudo-science gets bandied about carelessly. But heavens help the guy who isn't up to date on the latest revisions of the amphiboles, pyroxenes, or mica group. And bless the poor soul who strays off into the metaphysical around here. Do we really get to pick and choose at our leisure or are we trying to do good science?

Best Regards,

Al O

9th Sep 2016 17:45 BSTRonnie Van Dommelen Expert


Groutite ps. calcite, Nova Scotia, Canada

Stilbite ps. mesolite, Nova Scotia, Canada

Delicate dome with a little opening to see the interior. These often had a little ball of mesolite left in the middle.

9th Sep 2016 17:53 BSTD. Peck

This topic has always confounded me. Al, I, also, live with reasonably exact scientific definitions. When in doubt (at the risk of being xenophobic) I use the AGI's Dictionary of Geological Terms. I find that, in their definition, pseudomorph has two meanings. 1. Geological: "A crystal, or apparent crystal, having the outward form proper to another species of mineral, which it has replaced by substitution or by chemical alteration." 2. Paleontalogical: A natural cast in which the replacing material is a crystallized mineral, as calcite, pyrite, and more commonly, silica in the form of chalcedony."

Since my question precipitated this discussion, I would have to say that I was mineralogicaly/geologically correct (the objects in the first three photos are not pseudomorphs, but are fossils); but paleontologically incorrect, they are both pseudomorphs and fossils. So, I guess it depends upon what one considers to be his or her scientific specialty. :)-D

9th Sep 2016 19:30 BSTRolf Luetcke Expert


Great pieces and also great photos.

I am enjoying seeing the photos people add of favorite pseudos.

9th Sep 2016 20:31 BSTDan Costian

By the way of Don's mention of paleontological pseudomorphs, here is an amazing one, a flat, thin but large (11.3 x 6.6 cm) pyrite replacement of a fossil (identified as a Stromatoporoid from Cretaceous, Ozan Formation) found at the North Sulfur River, near Ladonia, TX.

It looks like a cabbage leaf :-)

9th Sep 2016 20:35 BSTRonald J. Pellar Expert

As Alfredo points out the literal meaning of the work "pseudomorph" has a very general meaning. Over time words will evolve to suit a particular field of endeavor and become part of the "lingo". This evolution is natural and ongoing and provides specific meanings that are appropriate for a small, or large, cadre of specialists to communicate among themselves. The problem seems to come in when the various "cadres" try to communicate outside their own group. As Don points out the AGI has defined the term "pseudomorph" more precisely for the geologists as a group. However, the groups that make up the field of geology may disagree among themselves! :-D It will be interesting to see how the definition of "pseudomorph" evolves in the future.

Since there are a log of pseudomorph specialist involved in this thread, I would like to ask their opinion on this particular pseudomorph that I personally collected at the Finch mine in Arizona some years ago. Raman spectra identified the replacing mineral as descloizite. what I would like to know is what is the mineral that it replaced? It was found in an open vug.

9th Sep 2016 21:17 BSTReiner Mielke Expert

"what I would like to know is what is the mineral that it replaced? " Maybe galena? looks a bit like a cubo-octahedron.

10th Sep 2016 04:16 BSTAlfredo Petrov Manager

Hard to judge a shape without a stereo image, but I tentatively agree with Reiner on galena.

10th Sep 2016 13:26 BSTRolf Luetcke Expert


I have quite a few specimens from the Finch and there is a bit of replacement going on there. The main ones are descloizite after wulfenite. Pretty much all the mineral specimens I have from there are covered again by quartz. Hard to tell in any detail on your piece.

Included here is one of the descloizite after wulfenite crystals.

10th Sep 2016 14:32 BSTDan Costian

Rhodochrosite pseudomorph after helvite from Kounrad Massif, Balkhash, Balkhash Region, Karagandy Province, Kazakhstan.

10th Sep 2016 16:48 BSTNorman King Expert

I have been following this thread, but haven’t jumped in yet due to other claims on my time. This is a good place to mention something that has been bothering me for some time. Below is a photo that was uploaded earlier in this discussion, and I see similar photos posted by dealers and others who think that fossilized snail shells, or perhaps corals from Tampa Bay, that they picture have been replaced by chalcedony. And this statement appears on the chalcedony page on “Another well-known pseudomorph is Chalcedony after coral. In the Tampa Bay in Florida, coral has been chemically replaced by Chalcedony, and its original form is preserved.” That statement is incorrect both paleontologically and mineralogically.

I added arrows to places in the snail photo that show bits of the remaining snail shell. I do not know the composition of that material, but I will assume it is still the original aragonite of the snail shell. The chalcedony has filled in the cavity of the shell–you know, where the soft parts of the snail were. Therefore it is an internal mold of the shell. We do not know if the shell material of the snails in this photo have been replaced by chalcedony, so we do not know if there is pseudomorphed aragonite there. You would have to analyze that material, or examine it in thin section, test it with acid, or do a hardness test on that material to determine whether it is a pseudomorph after skeletal aragonite. The definite chalcedony shown here crystallized in open space, so it has not pseudomorphed anything.

In paleontology, we refer to the cast of a shell when the shell material has dissolved and been replaced by another material–whether crystalline material or maybe just detrital clays. Internal molds are something else. Internal molds are among the most common preservational modes for fossils of shelled organisms. These snail shells are internal molds. Unfortunately, teachers in Earth science classes often get it wrong (calling them casts), and that is part of the problem.

In the case of the corals, the original aragonite seems to be all gone, and what is left are cavities in the enclosing rock that became lined (or entirely filled) by chalcedony (or it may be referred to as agate). So, the chalcedony/agate formed in much the way that geodes form. On the mindat gallery for agatized corals (, none of the fine skeletal structure of the corals is preserved, and they are actually neither molds nor casts. In fact, some of the internal areas seem to contain stalagtitic and/or stalagmitic chalcedony/agate or masses of quartz crystals within the cavities where the coral heads used to be. At the Mindat chalcedony gallery (, I did a search for photos from country “USA” with keyword “Tampa Bay” and found a lot of similar fossils, plus a snail shell posted by Rock Currier that may be a cast of the shell material, hence is a true pseudomorph. Some of the photos refer to “botryoidal corals,” but there are no botryoidal corals–they are referring to the habit of the chalcedony/agate as being botryoidal. Hence those cannot be pseudomorphic growths of chalcedony. A few of the photos show anatomical structure of the corals preserved around the outer portion of the coral head, and those portions of the fossils may be true pseudomorphs of chalcedony after coralline aragonite (but I don’t know the composition of those portions–if it is still the unaltered coralline aragonite, that would not be pseudomorphic). Somewhere in between, there would be aragonite partially replaced by chalcedony, and it seems to me that chalcedony would be pseudomorphic even though replacing merely tiny, and even microscopic, portions of the skeletal aragonite.

10th Sep 2016 17:06 BSTDan Costian

Another (classic) paleo-pseudomorph: rhodochrosite partly replacing a fossil shell from Kerchenskoe deposit, Kerchenskyi-ore basin, Kerch peninsula, Crimea peninsula, Crimea Oblast', Ukraine.

10th Sep 2016 19:19 BSTRonald J. Pellar Expert

Reiner, Alfredo, Rolf thanks for the suggestions. It does look cubo-octahedron, but I am not aware of any galena at that mine and the wulfenite there is typically in a bladed habit. I think more research on my part is needed.

11th Sep 2016 01:03 BSTDoug Schonewald


Thanks for the detailed lengthy description. I will forever consider these molds. Not unlike the limb casts that people fervently seek in Oregon.

These came out of a dark siltstone. They are encrusted with some pale stuff (unless you find them on the beach then they are naturally buffed clean) but I doubt if there is any aragonite on them since they have been cleaned in 30% muriatic acid. The material you refer to is likely some kind of clay that is impervious to at least HCl or a darker chalcedony with embedded impurities. I often thought I should try to clean them in oxalic acid but never seem to remember when I have the oxalic mixed up.

11th Sep 2016 02:16 BSTRolf Luetcke Expert


The calcite pseudomorphs after glauberite from Copper Canyon in the Verde Valley Arizona are sharp replacements.

A number of years ago green ones started showing up and we found they were artificially colored in someone's basement.

The natural ones from there come in three pseudos., calcite, aragonite and gypsum. The gypsum ones are hard to find in sharp crystals.

Aragonite ones often have visible crystals on the surfaces.

11th Sep 2016 03:46 BSTAlfredo Petrov Manager

But, Norman, if we consider only crystal pseudomorphs in the strict mineralogical sense, there are several different kinds, and one of them is casts, or the filling of a mold left by a vanished crystal, as for example in clay casts after vanished halite crystals. So how is that different from a mineral filling a mold left by a vanished animal? You might be confusing "replacements" and "pseudomorphs", with replacements being just one of several types of pseudomorphs.

On a somewhat related tangent, one of my pet peeves is people saying things like "siderite pseudomorph after calcite", which can't be a pseudomorph, because they can have the same morphology. It would be better to say "siderite replacement of calcite". But nobody wants to be friends with an obnoxious pedant, so in real life I'll hold my peace :-D

11th Sep 2016 04:21 BSTNorman King Expert

OK, Alfredo. In what way does a fossil or a portion of it have the external form of, say, aragonite? A fossil shows the form of an animal or plant. In the case of the latter, in what way is wood a mineral?

It would be best if people did not talk about fossils as being pseudomorphs. However, I did point out what a true pseudomorph would be for a snail and colonial coral. It is strictly a mineralogical consideration. As for petrified wood, Wikipedia states: “An example of this process (substitution pseudomorphism) is the replacement of wood by silica (quartz or opal) to form petrified wood in which the substitution may be so perfect as to retain the original cellular structure of the wood.” But formation of petrified wood is not pseudomorphism at all, strictly speaking. However, it may be getting there, since people misuse the word so much that eventually it takes on a new definition that would allow for wood to be a pseudomorph, since dictionaries are supposed to reflect usage rather than original or strict meanings. Definitions tend to become broader and less precise with time, not the other way around.

11th Sep 2016 05:19 BSTAlfredo Petrov Manager

In what way does a fossil or a portion of it have the external form of, say, aragonite?

- It doesn't. That's why aragonite pseudo after an animal is possible, but animal pseudo after aragonite is not possible. It only works in one direction (in the case of fossils anyway).

11th Sep 2016 12:04 BSTJohan Kjellman Expert

Alfredo Petrov Wrote:


> ... one of my pet

> peeves is people saying things like "siderite

> pseudomorph after calcite", which can't be a

> pseudomorph, because they can have the same

> morphology. It would be better to say "siderite

> replacement of calcite". ...

I was just thinking, isn't it so that "the pseudomorphing substance" usually is a polycrystalline aggregate or mass filling the voids of singular crystals or twins etc., and it is those previous single crystals that give the form. Thus when somebody says "siderite pseudomorph after calcite" or "cassiterite pseudomorph after feldspar" it is actually a shortening of "mineral-B crystalline aggregate/mass pseudomorph after mineral-A single crystal/twin"

just a thought...


11th Sep 2016 14:04 BSTDan Costian

Round concretion of greenish quartz pseudomorph after tabular calcite sprinkled with tiny crystals of dark ilvaite.

From Huanggang Fe-Sn deposit, Hexigten Banner, Ulanhad League, Inner Mongolia Autonomous Region, China.

A rare occurrence for this locality.

11th Sep 2016 19:00 BSTKelly Nash Expert

A chalcedony pseudomorph of gypsum, 37 mm., from my mineralogically-challenged home state of Nebraska. These have been found in several counties in the northwest part of the state, where the Chadron formation outcrops. This one's from Morrill County. They fluoresce green under SW UV. Although chalcedony often replaces gypsum, I haven't seen any "desert rose" chalcedony pseudomorphs like this from any other places. If someone else knows of similar ones from other areas, I'd like to hear about it.

11th Sep 2016 20:05 BSTReiner Mielke Expert

Hello Roland,

"It does look cubo-octahedron, but I am not aware of any galena at that mine " Maybe because it has all been replaced or altered.

11th Sep 2016 20:54 BSTErik Vercammen Expert


You have right, except for something rare like "uralite": apmhibole replacing pyroxene in an oriented way.

11th Sep 2016 23:00 BSTRolf Luetcke Expert



One of my favorite replacements in our whole collection is tiny but to me extremely fascinating.

It was on a fluorite specimen from Tombstone. Near the bottom was this little epimorph. It was several replacements of quartz after the fluorite with openings to be able to see inside.

12th Sep 2016 01:38 BSTRolf Luetcke Expert



I have one also and seems to be from Nebraska also. I got it in a batch of minerals I purchased at a rock shop in Mexico. It had no labeling on it at all and at first I thought it was the gypsum rose from our St. David Arizona area but it felt and looked wrong. That was when I did some testing and found it was a chalcedony pseudo. The only place I found these come from was Nebraska and that is where I assume this one comes from. It does look a lot like the other ones I have seen from there.

It sits next to a gypsum one that looks nearly identical in a cabinet we have.

12th Sep 2016 15:54 BSTDan Costian

Close-up of greenish quartz pseudomorph after radial prisms of ilvaite with second generation of tiny dark crystals of ilvaite.

From Huanggang Fe-Sn deposit, Hexigten Banner, Ulanhad League, Inner Mongolia Autonomous Region, China.

13th Sep 2016 14:42 BSTDan Costian

Calcite pseudomorph after goethite stalactites. Some goethite stalactites remained as such (at the right) while others were completely replaced not only glazed/covered with shiny calcite (see especially the other photo).

From Santa Eulalia District, Mun. de Aquiles Serdán, Chihuahua, Mexico.

13th Sep 2016 14:51 BSTRolf Luetcke Expert


Goethite epimorph after gypsum. At the bottom is a broken xl so you can see they are hollow. The others are pristine.

13th Sep 2016 14:58 BSTKelly Nash Expert

Not sure anyone on this thread has yet pointed out the great compendium of pseudomorphs, with many images, that Rock Currier put together here at "Best Minerals - P". In the first installment: "Pseudomorphs & Replacements A-B", he lists 10 types of pseudomorphs, and you can spend hours going through all the discussion and pictures of pseudomorphs found on the "P" mineral page (it would be nice to have the pseudomorph pages all together in one folder, but it's not difficult to find them there).

Thanks for the note on your Nebraska pseudomorph, Rolf. Looking at the "Pseudomorphs & Replacements - Quartz" page, assuming MIndat has covered the known localities for quartz pseudomorphs after gypsum, it does appear that those chalcedony-after-gypsum "roses" are most likely only found in northwest Nebraska.

13th Sep 2016 15:46 BSTErik Vercammen Expert


for your hollow goethite after gypsum specimen, the word epimorph looks more appropiate.

13th Sep 2016 16:15 BSTRolf Luetcke Expert

Yes Erik, that is why I had called it an epimorph. Here is another one and part of the epimorphs are coated by chalcedony, a bit different than the first one.

13th Sep 2016 17:01 BSTAlfredo Petrov Manager

Epimorphs are one of the kinds of pseudomorphs too. ;-)

14th Sep 2016 05:43 BSTDon Windeler


The closest example I've seen of chalcedony after gypsum that has the 'desert rose' habit is this piece out of the Renaud Vochten collection that was labeled "Passy, Paris, France." I don't have any more information on it or the locality. The specimen is 15 x 8.5 x 6 cm and the image is copyright Dan Weinrich, from whom I purchased the piece.

I'm on the road right now, but can try to dig it out when I get home if you have questions.



14th Sep 2016 15:06 BSTDan Costian

Hematite cast/pseudomorph after fossil shells in hematite shale from Tracy, San Joaquin Co., California.

14th Sep 2016 15:28 BSTKelly Nash Expert

Thanks for showing that pseudomorph of a gypsum rose, Don. I guess I was a little surprised to think that Nebraska might be the only source of them. I had thought that the gypsum "desert roses" tended to be found in non-marine environments (shallow lakes) and the Paris Basin is a thick sequence of marine evaporites, but I suppose that doesn't rule out the formation of similar clusters there (and their later replacement by chalcedony).

15th Sep 2016 14:36 BSTDan Costian

Goethite concretion (aka Indian paint pot) pseudomorph after pyrite with some limonite.

From Glen Cove, Nassau Co., Long Island, New York.

16th Sep 2016 14:02 BSTDan Costian

Scalenohedral calcite (some manganoan) coated/pseudomorphed by siderite. With minor sparkling submillimetric chalcopyrite.

From Kaiwu Mine, Hezhang Co., Bijie Prefecture, Guizhou Province, China.

17th Sep 2016 14:47 BSTDan Costian

Copper pseudomorph after azurite from Copper Rose Mine, San Lorenzo, Georgetown District, Grant Co., New Mexico.

17th Sep 2016 17:30 BSTDon Windeler

This isn't an especially colorful example -- and my photography doesn't help! -- but I acquired it because I'd never run across the replacement before. This is lazulite replacing a Carlsbad-twinned orthoclase in a porphyritic matrix. Locality is Cerro de Potosi, Bolivia, and the main crystal is 2.1 cm in length.

According to Alfredo P., these were reported in early descriptions of the district but he'd never seen one. This example came out of the Clifford Awald collection, who acquired it in 1956 from Ward's Scientific.



17th Sep 2016 21:22 BSTPavel Kartashov Manager

Gypsum pseudomorphose after Glauberite crystal from Camp Verde, Arizona. Excollection of Sam Elbin.



17th Sep 2016 21:26 BSTPavel Kartashov Manager

Copper pseudomorphose after Azurite concretions from Rubtsovsk, Altai, Russia.



17th Sep 2016 21:29 BSTPavel Kartashov Manager

Copper pseudomorphose after Cuprite crystals from Rubtsovsk, Altai, Russia.


17th Sep 2016 22:55 BSTRob Woodside Manager

I'm sorry Pavel but those photos will have to go into your User Gallery as the backgrounds are too distracting!:-D

17th Sep 2016 22:56 BSTRolf Luetcke Expert


That is one sharp gypsum after glauberite from the location in Arizona. I have collected there often and never found one so sharp. Great piece.

17th Sep 2016 23:07 BSTPavel Kartashov Manager

Hi Rob, these photos were made exclusively for this thread.;-) As you may to see, many photos from it were made on my kitchen table.

Thank you, Rolf. This PS was the present to my birthday this year.

17th Sep 2016 23:36 BSTRob Woodside Manager

Pavel, Thanks for sharing and Happy Birthday!

18th Sep 2016 00:00 BSTDon Windeler

Pavel, very nice & sharp glauberite replacement -- I'll echo Rolf's comment, in that I have one, but not nearly as good.

I've been vacillating as to whether to post this because the image isn't as sharp as I'd like, but maybe it'll provide some amusement to those who are really into these. In 2014 I put in a case with some of my pseudomorphs at the San Francisco Gem & Mineral Show. Here's a pic of the display. Usually it's possible to read the labels if you zoom in, but I must have moved a little and not taken a backup shot.

A few of my favorites include the calcite after aragonite? from Tasmania (back row, middle), kaolinite after agate from Brazil (back row, second from right), and cassiterite after orthoclase from Cornwall (front row, seventh from left) -- but of course, that's like picking out the kids you like best. :-D



18th Sep 2016 03:02 BSTAlex Earl Expert

There are so many interesting photos, thanks for sharing everyone, and thanks for starting this Rolf.

One of my favorite types of replacements are the Uraninite, as well as sulphide replacements after carbonized twigs and logs, which the Colorado plateau has in abundance. Here is one of my favorites that I recently acquired from Mineralogical Research Company, it is a Uraninite, Bornite, and Covellite (all intermixed and indistinguishable) replacement after a wooden fragment, from the Blue Lizard Mine, Utah.

Here is the mindat link to the image, it has more information in the description: []

18th Sep 2016 05:27 BSTStephanie Martin

Hi All,

Rolf, you had me at chrysocolla after cuprite! A stunning specimen (tu)

Really enjoying this thread. Wish I had more time to post new pics but I'll have to settle for some from my former uploads.

Here are three photos that I'll share today:

cerasite/mica group after cordierite & indialite

Kameoka City, Japan

(aka "cherry blossom" stones)

hematite after marcasite

White Desert, Egypt

rhodochrosite after sérandite

Mount Saint-Hilaire, Canada


stephanie :-)

18th Sep 2016 06:00 BSTJeff Weissman Expert

Here is one I've had in my collection for a while, coffinite and pyrite after dinosaur bone, with the bone vascules preserved quite nicely.

18th Sep 2016 06:02 BSTJeff Weissman Expert

And vivianite after belemnite fossils from Mullica Hill, New Jersey should be familiar to most of us...

18th Sep 2016 13:47 BSTRolf Luetcke Expert



First I want to thank all for the nice comments about the thread.

Second, Pavel, Happy Birthday! Again, Great gypsum after glauberite.

I have really been enjoying all the great pseudo. posts.

The one in these two photos I found a number of years ago at the Last Chance Mine in Courtland Arizona. I had it sitting for a long time, not sure of what had replaced the original cuprite. I did a lot of checking and finally contacted a close friend who knows minerals from Bisbee better than anyone. He said that he thought I was right about it being azurite after a pyramidal cuprite. He had seen this only one other place, in France.

Sorry about the photos not being up to what I would like but it was very hard to get a decent photo of this piece. If anyone has a photo of one from France, would love to see it.

Thanks again all, great photos of neat pseudomorphs.


18th Sep 2016 14:14 BSTDan Costian

Here is a nice combination of botryoidal siderite pseudomorph and epimorph after scalenohedral calcite with some dolomite and striated pyrite over the matrix (on the back). From Toroioaga Mine, Borşa, Maramureș Co., Romania.

18th Sep 2016 14:16 BSTTimothy Greenland

This is a bad photo, I know - the colour is off and I can't take another photo for the moment. I collected this at Chessy-les-Mines a few years ago now. The azurite, which is the initial replacement of the cuprite is, itself, giving way to malachite in spots... I'll try to find the necessary equipment and show you a better shot - if I get lucky!



18th Sep 2016 14:21 BSTDan Costian

Hi Stephanie,

I love your pseudos. Very cool, esp the group of cherry flowers sakuraite/cerasite.


18th Sep 2016 14:55 BSTRolf Luetcke Expert


Thank you for posting the French azurite pseudo. Nice to see such a sharp xl, mine are not nearly as sharp but to self collect one made my day.


This one goes along with the pseudo from Camp Verde you posted. These hit the market a while back and I wrote a story about them on my page. People were buying them as natural and we found they were coloring them.

This is one we colored to see how it was being done.

18th Sep 2016 14:58 BSTRolf Luetcke Expert


These calcite after ikaite from Russia are a nice pseudo that many will know.

18th Sep 2016 16:09 BSTKelly Nash Expert

There are several TiO2 paramorph-pseudomorphs that are interesting. I really like the rutile-after-anatase specimens from the Cuiabá District in Brazil, like this one:

18th Sep 2016 16:15 BSTKelly Nash Expert

And rutile after brookite, Magnet Cove, Arkansas, self-collected:

18th Sep 2016 16:36 BSTRolf Luetcke Expert


Loved your display of pseudomorphs, would have liked seeing it in person, thanks for posting it.

18th Sep 2016 16:42 BSTRolf Luetcke Expert


This is one given to me by Richard Graeme when I lived in Bisbee, a large malachite pseudo. after gypsum crystals.

18th Sep 2016 18:47 BSTRolf Luetcke Expert


Both of your pseudomorphs are great, very well crystalized.

18th Sep 2016 23:17 BSTRolf Luetcke Expert


This one I collected in Bisbee and I like the combination of the cuprite crystals on the limonite pseudomorphs after calcite crystals.

19th Sep 2016 00:16 BSTStephanie Martin

Dan - thanks and glad you liked them. I love all pseudomorphs but the “sakura ishi” are my absolute favourites of them all.

Timothy - I commend you on your effort for your azurite, an interesting and busy specimen. There’s something about Chessy pieces that don’t like to be photographed. I’m still trying to get a good result on my malachite after cuprite from there, so I can totally relate to your challenge.

Rolf - the flowery ikaite pseudos rank high on my list as well. I was pleasantly surprised when I discovered that we have some from Canada too! They do not have as much colour but I love them just the same since they are home grown. And your limonite after calcites seem to have a similar appearance in both form and colour to the ikaites, another striking specimen with those lovely cuprite accents. Just gorgeous!

Great contributions everyone - keep going with the great posts!

Here are a few more from Canada:

calcite var glendonite after ikaite

Eureka, Canada

schorl altering to muscovite

Villeneuve Mine, Canada

feldspar/microcline after scapolite

Griffith, Greater Madawaska Township, Renfrew Co., Ontario, Canada

7 x 6 cm (not yet uploaded)


stephanie :-)

19th Sep 2016 03:38 BSTPavel Kartashov Manager

Epimorphoses of marl after halite crystals, Rudnogorskoe Fe deposit, Irkutsk oblast', Eastern Siberia, Russia. Specimen and photo by Mikhail Moiseev, collected in 2016. Height of sample - 6 cm.

19th Sep 2016 13:34 BSTRolf Luetcke Expert


Great piece!! My wife likes color in her specimens but I tend toward shape as much. Faithful following of the original halite.

Here is one a geologist friend collected while sampling underground at the Spotted Horse Mine in Montana. He found tiny stringers of talc in the last workings with these pseudomorphs of "sponge" gold, he called it. It is not solid but a mass of tiny gold particles following what was probably sylvanite.

19th Sep 2016 14:25 BSTDan Costian

Limonite covering/pseudomorphing botryoidal goethite (chocolate colour:-) from Tower mine, Luis Lopez manganese District, Socorro Co., New Mexico.

19th Sep 2016 16:04 BSTAlex Homenuke Expert

Here is a set of 15 pseudomorphs supplied by Ward's. See photo of original list for details. Many are display quality. Does anyone have an idea of the date of issue?


19th Sep 2016 17:46 BSTRolf Luetcke Expert


Cool collection from Wards. They had some great stuff over the years. Unfortunately they started in the late 1800's so hard to tell unless a date on the stationary.

Here is a neat pseudomorph of hematite after baryte from a friend from Virginia.

19th Sep 2016 22:48 BSTToby Seim


These Pseudo's are very rare, Hematite after Epidote crystals, covered with a new generation of mini quartz crystals. Recently dug at the remote locale deep in the Cascade Mountains of Washington State. Cant wait to clean them up. Cheers!

20th Sep 2016 00:11 BSTRolf Luetcke Expert


Great find and those should clean up nicely.

Here us a pseudo of chrysocolla after gypsum from the Ray Mine. A friend gave this piece to me a few years back and it is one I really like.

20th Sep 2016 01:39 BSTKelly Nash Expert

Fun subject & wonderful photos, everyone! The rutile ps. of brookite I posted earlier was found at Magnet Cove in sediments at Cove Creek at "Ross Dairy Farm" in 2004. The process we used was to shovel up gravel from the creek bed, screen it, use a magnet to pull out all the magnetite, which was the majority of the pebbles, and then comb through the leftovers. Most of the time, the magnetite was not very interesting, but this little magnetite after pyrite caught my eye. Not very attractive, but just a neat pseudomorph, in my opinion.

20th Sep 2016 05:12 BSTStephanie Martin

Awesome specimens everyone! Lots of exotic stuff.

Rolf - that Ray Mine piece is another chrysocolla marvel. Truly breath-taking. And the “sponge gold” was quite intriguing.

Alex - that’s a cool kit you have there, quite nostalgic. Sometimes those older specimen kits are hard to beat for simplicity.

Don - I loved your display on the previous page. I tried to magnify to see more detail. One thing I noticed is that colourful pseudos really steal the show since they are less common in general. You have quite the cabinet!

Kelly - that’s a neat magnetite after pyrite. You have many drool worthy specimens.

Sorry for the less than stellar photos for this set, I am limited to using my phone camera for the time being.

Here is some plain old fare of limonite after pyrite from Chestnut Hill, West Hempfield Township, Lancaster Co., Pennsylvania, USA

Two more thumbnails from USA, one with a little colour

smithsonite after dolomite

Rush Creek, Marion County, Arkansas

(exact mine unknown)

hematite and micro topaz after almandine

Thomas Range, Utah

Some of these are quite interesting as they have bixbyites also growing on them, I chose one here that did not in order to see the former dodecahedron shape. (Kelly, your specimen in the gallery is outstanding, just saying…)

20th Sep 2016 08:35 BSTGreg Dainty


Quartz replacing garnet, Dalnagorsk, Russia, Size is 120 x 90 x 70mm. The beautiful sparkling nature of this is not captured by the pic.

20th Sep 2016 09:13 BSTGreg Dainty

Garnet after tectonic quartz , Bor Pit, Dalnegorsk, Russia, size is 98 x 38 x 20mm. Collected mid 1990s , ex Allen Arnold collection.

20th Sep 2016 15:17 BSTRolf Luetcke Expert


Great photos, what I had hoped when I started the thread, wonderful pieces I have never seen examples of. Greg, the garnet after quartz is a real winner.

Kelly, very nice explanation of the find of the magnetite after pyrite.

Went through my photo files and so far have found 68 examples of pseudos in our collection, sure more are hiding in there.

This is one I like because of its delicacy. Chrysocolla after morgenite from Arizona.

20th Sep 2016 17:24 BSTRichard Gibson

I didn't see one of these in the thread, sorry if it is a repeat. Copper after sixling twin of aragonite, Corocoro, Bolivia. 2.5 x 3 cm.

20th Sep 2016 18:01 BSTDan Costian

Hematite pseudomorph after garnet on champagne topaz crystal with rhyolite coating and inclusions.

From Maynard's claim, Thomas Range, Juab Co., Utah.

20th Sep 2016 18:13 BSTStephanie Martin

For those who don't use the link, here's Dan's piece ~ it's a beauty :-)

20th Sep 2016 18:55 BSTRolf Luetcke Expert

I agree, that hematite on topaz is a great specimen. Really enjoying all the wonderful posts.

20th Sep 2016 21:40 BSTRichard Gunter Expert


MSH has an abundance of pseudomorphs after hexagonal whatsits. The photo posted as # 529169 is the most common prism of Analcime possibly after Cancrinite. The posted photo is a rarer pseudomorph. The white prismatic crystals in the photo are a 3-D aggregate of highly twisted 2 mm carbonate crystals after a hexagonal whatsit. I think the original may have been Willemite but there is no fluorescence left.

21st Sep 2016 05:48 BSTStephanie Martin

Greg –those are darlings from Dalnegorsk, I never get tired of seeing the marvels from that location.

Richard G – That is a really nice sized sixling sample.

W. Richard - you can get lost in that MSH treat!

Rolf – I never stopped to count how many pseudos I actually have but I think it will be fun trying to figure it out (it’s probably quite a few). Of course it depends on how you define the term.

My next set is epimorphs. Sorry if I’ve been hijacking the thread a bit, I wanted to get some posts in before my available down time window disappears. I’ll be relegated back to lurking soon :-)

quartz casts after glauberite

Houdaille Quarry), Little Falls Township, Passaic Co., New Jersey, USA

1978 ex Beth Gordon (per label)

3 x 3 cm


dolomite after calcite, and 2nd generation calcite

Boldut Mine, Cavnic (Kapnic; Kapnik), Maramures Co., Romania

4 x 3 cm


quartz var chalcedony after twinned (butterfly) calcite


Maharashtra, India

(hollow as evidenced from the bottom)

6 x

21st Sep 2016 06:16 BSTLawrie Berthelsen (2)

These weird chalcedony formations from Morocco seem to me to be pseudomorphs, what do you think? The white sections are crystal-shaped chalcedony, but they do not seem to show any of the usual quartz shapes. They are also mostly convex, as opposed to geode-shaped. And how on earth has the darker chalcedony formed, seemingly to have been extruded out of the white sections?


The more agates I see, the more questions I have.


21st Sep 2016 14:09 BSTDan Costian

Goethite epimorph after selenite from Santa Eulalia District, Mexico.

It looks like Stephanie's quartz cast after glauberite only it's black :-)

21st Sep 2016 14:15 BSTRolf Luetcke Expert



Great pseudomorphs and quality of photos. Love that chalcedony after butterfly twin.

I had not counted how many we have until people seemed to like the thread and I went through a couple of old lists I had and went through my photos to assemble a pseudo. folder. There are 71 I have assembled so far. Have to get the brain in gear to see if I can remember other pseudos I have forgotten.

The one in this photo is an odd one. At the Last Chance Mine in Arizona are lots of micro crystals, most variety of crystal habits of azurite I have ever seen and came across one piece that had chrysocolla replacing the azurite. Some of the crystals are completely replaced, some you still see the inner azurite.

Having a great time seeing all the great pseudos and again, Stephanie, nice ones.


21st Sep 2016 15:43 BSTRui Nunes Expert

And one from Portugal

turquoise after libethenite from Miguel Vacas Cu mine.

21st Sep 2016 17:22 BSTRolf Luetcke Expert


Love the turquoise after libethenite, had not seen one like it.

Love those odd replacements.


My wife loves casts and epimorphs.

This is one she picked up for $3 from a private dealer.

21st Sep 2016 17:48 BSTAlex Earl Expert

I finished photographing this one yesterday, and just added it to mindat. It is quite an interesting piece. I collected it from the Colorado No. 1 Mine, Tintic District, Utah. These are octahedrons of Magnetite with spheres of Goethite on Quartz. As you can see, some of the Magnetite crystals have pseudomorphed into Goethite. This suggests one of two things happened, either some of the magnetite crystals were selectively oxidized, or that there were two phases of Magnetite formation, with oxidation occuring between the two. I think the latter is what happened, it is an interesting piece to think about.

21st Sep 2016 18:10 BSTRolf Luetcke Expert


Love those kinds of pieces and yours is a really nice one.

Those separate deposition and replacements one would love to "be there" when it was going on to see just what was taking place.

Really like the one you posted Alex.

21st Sep 2016 18:36 BSTAlex Earl Expert

Rolf, I am glad you like it!

Here is another one on the same specimen, but I am not so sure what it is exactly. It looks like a Quartz (epimorph?) after/on something, I think Wulfenite. The yellow color is probably some Mimetite coloring the Quartz, there are Mimetite crystals elsewhere on the specimen. This piece has me intrigued, so much was going on in such a small area (the piece is only about 4cm at the most).

The FOV is 4mm

21st Sep 2016 20:57 BSTDan Costian

Fan-like crystal cluster of hedenbergite pseudomorph after ilvaite.

Looks like a bunch of sky scrappers seen from above.

From No. 1 Mine, Huanggang Fe-Sn deposit, Hexigten Banner, Ulanhad League, Inner Mongolia Autonomous Region, China.

21st Sep 2016 20:59 BSTDan Costian

Stephanie Martin Wrote:


> For those who don't use the link, here's Dan's

> piece ~ it's a beauty :-)



Thank you, Stephanie. I am glad you like it.

21st Sep 2016 22:39 BSTDennis McCoy

here is an antique pseudomorph specimen from my collection; limonite after siderite.



22nd Sep 2016 03:19 BSTNorman King Expert


Sorry I’m late to respond, I haven’t looked at this thread for several days. The chalcedony seems to be replacing fossil snail shell material (which is aragonite), or has crystallized around it. It is hard to make out how many snail shells there are; some of the chalcedony seems to be bridging a gap between two or more snail shells. The dark material was probably pyrite at one time (or likely a mix of clay that was sedimented into the empty shell, and pyrite that precipitated with it in the enclosed space of the shell), but is now goethite replacing pyrite. So you seem to have a double pseudomorph.

22nd Sep 2016 05:58 BSTLawrie Berthelsen (2)

Hi Norman, thanks for your reply, and for your interesting theory. I have looked at hundreds of these agates, and I can not see anything resembling snails or snail shells. The white chalcedony looks to have replaced previously crystalline balls, and the dark material is also chalcedony, not goethite replacing pyrite, as you suggest. If you do an eBay search for " chalcedony, Morocco", you will see many of these strange formations. While every one is different, they are all recognisable as being the same formation.

Regards, Lawrie.

22nd Sep 2016 06:33 BSTDon Windeler

Haven't posted to the thread in a few days, but I've been watching. This may be inspiration to steal my wife's camera and figure out how to get some better lighting for pics, as most of the ten (+/-) flats of pseudomorphs I have aren't photographed in MinDat.

Greg, I love the quartz ps. garnet / garnet ps. quartz pairing. Never seen the latter before and I really like two-way mineral pairs like that.

Stephanie, thanks for the comments on the display. I'm frustrated it wasn't possible to read the labels, as that would have made it more interesting for folks.

Here's one of the favorite pieces in my collection, though I'm still not entirely sure whether these count as pseudomorphs: a copper replacement agate from Michigan.

A different photo of this pair was in the Crystal Gazers supplement of the MinRec.

For something completely different and undeniably a pseudomorph, here's a leonite ps. picromerite from Germany.

Simple dehydration in this case. Whenever I happen to open up the drawer in which it's currently residing, I ask it to stop and be happy with it's current state of existence. :-)



22nd Sep 2016 13:48 BSTRolf Luetcke Expert


This is one from the Last Chance Mine in SE Arizona. I have a collection of all the various forms the azurite takes at this mine and in some places the azurite has been replaced by chrysocolla. This one, unlike the other photo where you can still see the azurite, has been totally replaced but you can see the fan-like bladed habit of the original azurite. I have ones of azurite that have the same habit.

22nd Sep 2016 13:53 BSTRolf Luetcke Expert


This one is a descloizite replacing vanadinite from the Commercial Cramer Mine in New Mexico.

22nd Sep 2016 14:12 BSTDan Costian

Chalcedony pseudomorph after baryte with packs of parallel needles. It comes from McDermitt, Humbold County, Nevada.


22nd Sep 2016 16:03 BSTJeff Weissman Expert

A more unusual one, and I had this EDS identified as well. A former magnesiochromite crystal in which the Mg and Fe have been removed, leaving behind Cr-O bearing dark green colored eskolaite. You can see a rim of iron oxides, reflecting the original crystal shape, around the eskolaite.

23rd Sep 2016 06:36 BSTStephanie Martin

Continuing to enjoy all the interesting posts, no shortage of variety!

Rolf - I find that bargain pieces hold a special place, they may not be museum quality but scoring a good deal feels satisfying. It's like a juicy secret and it's amazing how well you remember it! Once I found a half dozen thumbnails of those turquoise after apatites from Sonora. They were of average quality but for $3 each I could live with that and snapped them up. I couldn't stop at just one for that price? :-D. Here below is another one that I picked up, if you count coral replacement as part of the category. And yes I also continue to rediscover pseudmorph specimens that I didn't remember that I had.

As Norman commented back on page 3, you can see the outline of the original coral skeleton in somewhat greyish agate and then the interior that has been filled with more white, grey and blue chalcedony, that according to Norman's explanation is not part of the replacement but a filler. I don't know how common the blue tones are but usually we see the white/tan/brownish type up here in Canada. Perhaps they are more available and inexpensive close to the source in Florida, but for the whopping price of $2.50 (Canadian) I didn't have to think twice. (Sorry, another cell phone shot).

quartz var agate/chalcedony after coral

Tampa Bay, Florida USA

approx 9 x 6.5 cm

23rd Sep 2016 12:22 BSTNiels Brouwer

This thread really is a magnificent demonstration of the intriguing amount of variety that pseudomorphs have to offer. Thanks for sharing!

I don't have that many pseudomorphs in my collection, but this quartz psm. calcite from Romania definitely is one of my favourites. I love the contrast between the bright white former calcite scalenohedrons and the dark sphalerite and bournonite matrix. With the calcite up to 12 cm tall it is a very large and three-dimensional piece in person, which is quite challenging to capture in a 2D photograph.

23rd Sep 2016 13:58 BSTDan Costian

Specular martite (hematite pseudomorph after magnetite) partly dissolved/hoppered.

From Payún volcano, Altiplano de Payún Matru, Malargüe Department, Mendoza, Argentina.

23rd Sep 2016 14:11 BSTRolf Luetcke Expert


I remember seeing those turquoise pseudos and something didn't seem right to me at the time and I didn't buy one. I didn't trust the dealer that had them was the problem, had some fakes before so I passed.

As for picking up several of something, I came across some hematite roses from China one time, $5 a piece and I got all the nice ones they had. Never saw them again and they are huge compared to other hematite roses I have seen, never saw more. Finally pinned down the locality after posting the photo on mindat. They only had China on the label. Not actually along with this thread but your story brought up this one about hematite.

Back to this thread, my wife and I were at a small mine near Tombstone and she saw a glint of golden color and picked up one piece and it is the nicest piece we found at the San Diego Mine. It is a hematite with a golden sheen after calcite. Unfortunately the piece was damaged but some of the crystals are as sharp and complete as can be.


I have one of those quartz after calcite from the same location! Nice to see another one. Ours is huge, 18x20cm. It was in a collection we purchased.


23rd Sep 2016 14:57 BSTJamison K. Brizendine Expert

Not the greatest photo, but here is a Quartz after fluorite, with the original fluorite dissolved (an epimorph). Qinglong Mine, Guizhou Province, China. The entire specimen is 9.7 cm x 6.3 cm x 10.1 cm

23rd Sep 2016 16:19 BSTAlex Homenuke Expert

Here's a couple more. The first is talc after quartz, which amaze me that they survive. The second is just pretty!

Handmade display box and historic label are also interesting.


Muscovite pseudo spodumene, Oro Fino Mine, Minas Gerais, Brazil with similar shaped spodumene from the same general area.

23rd Sep 2016 17:04 BSTDennis McCoy

here is a chalcedony after aragonite, also an epimorph, from Arizona.



23rd Sep 2016 17:45 BSTVolkmar Stingl

This is a hollow quartz epimorph after fluorite octahedrons. From Yongping Cu-mine, Yongping, Shangrao Pref., Jiangxi Prov., PR China. 6.5 x 4 x 3 cm.

23rd Sep 2016 20:31 BSTRob Woodside Manager

Sar-e-Sang has produced some pretty wild replacements:

Glowing Marialite under Orthoclase (LWUV)

Orthoclase after Marialite
Orthoclase after Marialite

Diopside with minute Ferrous/ Ferric coating
Hauyne replacing Pargasite

Hauyne after Phlogopite
Hauyne replacing Phlogopite

Gonnardite replacing Hauyne
Gonnardite and Thomsonite replacing Hauyne

24th Sep 2016 01:28 BSTRolf Luetcke Expert


Great group of pseudomorphs!!

Here are a couple more.

The first is a bit ugly but interesting, hematite after cerussite, twinning can still be seen. Piece is from Bisbee.

The second one is chalcedony quartz after aragonite from Chihuahua Mexico.


24th Sep 2016 07:20 BSTVolkmar Stingl

Martite (hematite after cubic-cuboctahedral magnetite; XRD analyzed) with smoky quartz. Martite 3 mm. From Ahornspitze, Zillertal Alps, Tyrol, Austria.


24th Sep 2016 13:33 BSTErik Vercammen Expert


I like yor pics, but I have the impression your "quartz after aragonite" from Chihuahua are in fact former calcite crystals: a steep rombohedron cut by the pinacoid. Intresting form by itself!

24th Sep 2016 13:41 BSTDennis McCoy

Pseudo's after Aragonite seem to be fairly common. The following single crystal examples are from my collection.

From left to right, chalcedony, dolomite, calcite/quartz, copper, chalcedony

24th Sep 2016 14:40 BSTDan Costian

Grape-like crandallite pseudomorph after wavelite. From Mauldin Mt., Montgomery Co., Arkansas.

24th Sep 2016 16:09 BSTHarold Moritz Expert

Been following this thread for days, too busy to add until now. I have tons of ps. examples from Connecticut, and Tilly Foster Mine, near Brewster, NY. But for now, based on earlier posts, I am adding this chalcedony ps. after echinoid. My aunt gave it to me in 1976, she dug it up in her garden outside Hamburg, Germany. I havent posted it to mindat cuz I dont have an exact location, but geologically that part of the country I believe is glacial deposits and it obviously was not "in place". I suppose it could be posted at the "state" level. Anyway, I also have an old Ward's teaching model & label of the same species, which gives the name as Ananchytes ovata, Lam., from chalk at Meudon, France (probably Cretaceous). Specimen is 38 x 32 x 27 mm.



24th Sep 2016 18:26 BSTRolf Luetcke Expert


The ID on the aragonite pseudo came from Peter Megaw, he looked at the photos and said they were aragonites replaced by chalcedony.

The photo here is a quartz epimorph after smithsonite from the 79 mine in Arizona.

24th Sep 2016 20:00 BSTErik Vercammen Expert


Aragonitie is orthorombic while these (ex)crystals look trigonal. But I admit, pics are somethimes difficult to judge.

24th Sep 2016 20:27 BSTDan Costian

Quartz pseudomorph after anhydrite from Prospect Park Quarry, Prospect Park, Passaic Co., New Jersey.

Interesting shape.

24th Sep 2016 20:38 BSTHarold Moritz Expert

Quartz epimorphs on dissolved anhydrite, Bates Rock Road, Southbury, Connecticut.

25th Sep 2016 01:56 BSTDan Costian

Well grown, elongated, golden crystals of calcite pseudomorph after unknown fossil, probably a clam. These Floridian specimens found West of Fort Lauderdale at the limit of the Everglades, Broward County are less known than their counterparts from the Ruck Pit but of a similar quality.

Looks like a lotus bud :-).

25th Sep 2016 15:10 BSTDennis McCoy

Here are three examples of Chalcedony casts of aragonite clusters from the Western Hemisphere.

left front is a partially filled Coyamito agate (Mexico); right front is from Argentina, center rear is a previously posted example from Arizona.

25th Sep 2016 16:21 BSTRolf Luetcke Expert


This stibiconite after stibnite was one we got in the purchase of a collection. It is the largest one we have in our collection at 45mm long.

25th Sep 2016 16:29 BSTDan Costian

Nice stibiconite, Rolf. I have one which is 12 cm long but not as cool as yours :-(

From Xikuangshan Sb deposit, Lengshuijiang Co., Loudi Prefecture, Hunan Province, China.

And here is some unusual lamellar and bent silver pseudomorphed to acanthite from Imiter Mine, Imiter District, Djebel Saghro, Ouarzazate Province, Souss-Massa-Draâ Region, Morocco.

25th Sep 2016 17:05 BSTKelly Nash Expert

Pale blue chalcedony after melanophlogite or fluorite, 50 mm., Trestia, Romania. These have been identified as pseudomorphs after fluorite (including on the Mindat locality page, and most of the photographs of psuedomorphs from there), but apparently recent research has suggested they are actually melanophlogite replacements. (See the discussion at: New Melanophlogite Localities in California), and I am seeing that some dealer specimens are now calling them chalcedony after melanophlogite. Think I'll add a note to the locality page about that.

25th Sep 2016 19:28 BSTNiels Brouwer

I have been intrigued before by these supposed pseudomorphs after fluorite, Kelly. Fluorite is such a rare occurrence in Romania that I found it rather puzzling that there would have been these large clusters of cubic crystals before they were replaced by the chalcedony. Sounds quite plausible that it would be another species than fluorite after all. :)

25th Sep 2016 21:26 BSTRolf Luetcke Expert




Thanks for the comment about the stibiconite. In that collection I bought there was a Japan stibnite that looked pretty much just like the stibiconite before the replacement.

The two here are not necessarily uncommon, just pretty. Nice to have collected those myself.

Have been greatly enjoying all the postings, have always loved pseudomorphs.

25th Sep 2016 22:12 BSTKelly Nash Expert

Powellite ps. after molydenite (there is still some molybdenite showing on the other side), 49 mm. This was found by Terry Szenics in 1994 at the Jardinera No. 1 Mine in the Atacama Region of Chile, the same mine where szenicsite was discovered.

25th Sep 2016 23:28 BSTRolf Luetcke Expert


That is a great pseudo. Another one I had not seen before.

Does it do anything under UV? The powellites I have collected do a nice yellow under short wave but a pseudo may or may not, makes me curious.

26th Sep 2016 00:43 BSTDennis McCoy

Rolf, this epimorph from South Africa has a similar crystal shape to the chalcedony after aragonite you posted a few days ago.



26th Sep 2016 15:59 BSTDan Costian

Pyrite pseudomorph after unidirectional grown, bent, spear-like marcasite from Ross Co., Ohio.

Odd, stalactiform shape.

26th Sep 2016 17:42 BSTRob Woodside Manager

Kelly, please add that powellite after moly to the galleries.

26th Sep 2016 21:27 BSTHarold Moritz Expert

Some pseudomorphs from the gas vesicles in the Orenaug Basalt, Southbury, Connecticut.

Prehnite ps. after quartz:

Prehnite ps. after analcime:

Pumpellyite ps. after analcime:

Quartz ps. after anhydrite:

27th Sep 2016 13:40 BSTDan Costian

Cervantite pseudomorph after stibnite from Gallos Mine, Sierra de Santa Rosa, Mun. de Mazapil, Zacatecas, Mexico.

27th Sep 2016 19:13 BSTDan Costian

1.8 cm-tall sharp double-terminated anatase floater replaced by rutile from Anatase-rutile occurrence, Cuiabá District, Gouveia, Minas Gerais, Brazil.

27th Sep 2016 21:44 BSTHarold Moritz Expert

Cool anatase/rutile paramorph. Speaking of the latter mineral, here are a few ilmenites pseudomorphed by a mix of rutile/hematite/magnetite from Litchfield, Conn. (it isnt always obvious the ilmenite is replaced unless a magnet is used, then you can really feel it!):

27th Sep 2016 21:53 BSTHarold Moritz Expert

Here's one that isnt in mindat yet, but is on page 273 of the Min Record supplement - Mineral Collections in the American Northeast. Fourmarierite ps. after uraninite with unaltered uraninite core and uranophane crust in weathered felspar, 7 cm from the Bisundi Pegmatite, Bhilwara Dist., Ajmer Div., Rajasthan, India. Eric Quinter specimen, ex. Richard V. Gaines:

28th Sep 2016 05:56 BSTVolkmar Stingl

A pseudomorph of siderite after calcite, with younger calcites on top. From Yongping Cu-mine, Shangrao pref., Jiangxi prov., China. Longest Diameter ca. 8 cm.

29th Sep 2016 13:32 BSTRolf Luetcke Expert


These were sold as borax crystals but on doing a bit of research they are pseudomorphs of tincalconite after the borax.

29th Sep 2016 13:36 BSTRolf Luetcke Expert


Slightly atypical pseudomorph.

29th Sep 2016 13:40 BSTHarold Moritz Expert

Good catch, I forgot about those tincalconites!

Here's a bunch from the US Borax Pit mine in Boron, California - normal light and under LW UV light.


29th Sep 2016 14:05 BSTDan Costian

Box epimorph of druzy quartz after anhydrite with salmon-color stilbite.

From Nashik quarry, Nashik District, Maharashtra, India.


29th Sep 2016 14:36 BSTPavel Kartashov Manager

Rolf Luetcke Wrote:


> > Slightly atypical pseudomorph.

Dear Rolf,

these aren't pseudomorphoses, but oikocrystals (variety / private case of poikilocrystals).

29th Sep 2016 16:09 BSTRolf Luetcke Expert


That was why I had put "atypical" because although it is a replacement it is kind of fudging with being a pseudomorph. Didn't know the proper phrasing and you put it, thank you!

Here is a copper after cuprite from Bisbee.

29th Sep 2016 17:03 BSTRichard Gunter Expert

Hi Rolph:

I do not think those sand calcites are a replacement. In many sand sequences the infilling calcite forms concretions if the cement is discontinuous or forms a sandstone if it is continuous. In the case of the sand calcites the calcite cement formed crystal outlines rather than the rounded aggregates typical of concretions. The cement fills in the pores of the sand in all three cases without reacting with the sand particles.

29th Sep 2016 17:55 BSTPavel Kartashov Manager

This is one old sample from Kalba range rare-metal pegmatites without exact locality. Many years it puzzling me.

You may to see here "sugar" albite replacements after four tetragonal crystals. They are exactly tetragonal and composed by tetragonal prism doubleterminated by dipiramyd.

I don't know any tetragonal mineral in these natro-lithium pegmatites which would be able to be replaced by albite and forms crystals of such size (minor squares on carpet are 7 mm). Zircon or xenotime can't.

At the left side of the first photo is visible plate of former spodumene also replaced by similar but different albite (more coarse crystalline and more clear white). Other minerals are smoky quartz, greenish muscovite, white unaltered orthoclase and minor tantalite.



29th Sep 2016 17:57 BSTPavel Kartashov Manager

One more shot of the same sample.

29th Sep 2016 18:16 BSTPavel Kartashov Manager

One more gummite psedomorphose.

This is old times, pre WWII sample of large north-karelian uraninite (var. Broggerite) crystal (its cubic outlines are still preserved from one side) replaced by orange thorian Curite (in its core) with bright-yellow Casolite/Soddyite outer zone. Sample matrix is black biotite penetrated by later dull-yellow uranophane fibrous films.



This sample was used in the experiment, described in,59,108437,110837#msg-110837

29th Sep 2016 19:59 BSTRolf Luetcke Expert


I see what you mean. I have the photo in my pseudo folder and it really shouldn't be in there.

We have "sand roses" here in SE Arizona, gypsum that grew in sand and they are just like the sand calcites.

Thank you Pavel and Richard for the clear picture.


29th Sep 2016 21:16 BSTRichard Gunter Expert

Hi Rolf:

Baryte roses in Oklahoma are formed in the same manner.

29th Sep 2016 21:31 BSTMark Heintzelman Expert

As they do also at the sand pit in Rockenberg, Hesse, Germany

'Rockenberger Röschen' Sand Pit, Rockenberg, Taunus Mountains, Hesse, Germany) ex. Alfred Stevenson collection. 2-7/8 x 2-3/8 x1 inch

30th Sep 2016 01:03 BSTReiner Mielke Expert

Great sample Pavel!

30th Sep 2016 01:39 BSTMark Heintzelman Expert

Decomposition pseudomorphs from Germany/Czech Republic, so call "Pseudolucite", rapid cooling Hi-temp lucite that separated out into a composite of Orthoclase and Nepheline.

from Oberwiesenthal, Erzgebirge, Saxony Germany, the vast majority come from various diggings across the border at Loucna, Czech Republic .3 x 3 x 2cm

30th Sep 2016 02:00 BSTMark Heintzelman Expert

Stevensite pseudo after Pectolite on Prehnite from the Type Locale, Bergen Hill, Hudson Co., New Jersey, USA.

Old Ward & Howell Label circa 1875-1891, ex. Michigan College of Mines collection. 3 1/4 x 2 1/2 x 1 inches

30th Sep 2016 14:00 BSTHarold Moritz Expert


Thought a lot about your pegmatite albite pseudos (I have collected many, many pegs, and looked through several comprehensive books) and based solely on the habit, the possible original minerals could be cassiterite, tapiolite, rutile, xenotime, or zircon. I would not expect albite to pseudomorph any of these minerals, but they sure look like zircon crystals.

30th Sep 2016 14:05 BSTHarold Moritz Expert

Speaking of tetragonal pseudos, here are some ferberite after scheelite from Trumbull, Connecticut, USA. There are many examples posted of this classic. Some under the old series term "wolframite" despite analyses nearly 100 years ago showing they are ferberite.

30th Sep 2016 14:17 BSTDan Costian

Here is a quartz pseudomorph after calcite where the mudstone in the original septarian nodule was dissolved and only the walls (septa) remained. It is called septarian core, septarian web/concretion, hollow turtle stone or melicaria.

From Julimes, Mexico.

To see the children photos please open

30th Sep 2016 15:03 BSTRolf Luetcke Expert

I wanted to message here yesterday but something was not working.


I have loved every photo/specimen you have posted here. The uraninite replaced by curite/soddyite is really great. My wife loves the U minerals.


Loved the ferberite after scheelite, such a nice sharp xl.


Very nice quartz after calcite.

I found the one here myself at a small mine near us.

I found little actual pyrite but lots of replacements but this one was a bit different, black hematite on the inside of the crystal and coated by either another color of hematite or limonite.

30th Sep 2016 16:01 BSTDan Costian

Thank you, Rolf.

Here is another "melicaria": alveolar hematite left after the clay was weathered out of a septarian nodule where the cracks had been infiltrated with hematite. It's a large specimen (12.3 cm x 6.1 cm) from Dallas,TX.


30th Sep 2016 17:20 BSTPeter Andresen Expert

Once upon a time there was a 80cm long beryl... Now completely replaced with a fine grained mixture of albite, bertrandite and muscovite. In situ picture, I hope it's still there...

30th Sep 2016 17:26 BSTRolf Luetcke Expert



This is a piece I found in Bisbee which is an epimorph of goethite after hemimorphite with some yellow limonite as an outer coating. Second photo shows the inner hollow nature of the crystals and the fibrous structure of the goethite.

These were found on the old 1880's railroad overburden near Fairbank, where material from Bisbee was used to build the rail bed.

2nd Oct 2016 01:03 BSTDan Costian

Feather (Feder, in German) pyrite pseudomorph after pyrrhotite from Pfaffenberg Mine, Neudorf, Harzgerode mining district, Harz, Saxony-Anhalt, Germany.

2nd Oct 2016 13:44 BSTDan Costian

Tennantite with a spot of rhodochrosite. Probably a pseudomorph after enargite.

From Zacatecas, Mexico.

3rd Oct 2016 14:14 BSTDan Costian

Plumbogummite pseudomorph after divergent elongated barrel-type pyromorphite. Nice color contrast.

From Yangshuo Mine, Yangshuo Co., Guilin Prefecture, Guangxi Zhuang Autonomous Region, China.


3rd Oct 2016 14:58 BSTHarold Moritz Expert

Some classic pseudomorphs of spodumene from the Fillow Quarry, near Branchville, Connecticut:

Eucryptite/albite parallel growth fibers after spodumene:

"cymatolite" (parallel growth albite/muscovite fibers) after eucryptite after spodumene

eucryptite, cymatolite and "pinite", all after spodumene:

3rd Oct 2016 16:24 BSTToby Seim


This is a better picture of my previous post. This used to be a terminated epidote crystal before it was replaced with hematite and a later generation quartz crystal coating. This specimen also has another terminated piece perched along with it. Self-Collected this year. They are hard to tell what they look like initially because they are caked with dirt... I dont know if i am bringing home some prime specimens or a bunch of turds LOL.

4th Oct 2016 14:43 BSTDan Costian

Pseudomorphed/covered green muscovite books, associated with spessartine and microcline.

From Wushan Spessartine Mine, Tongbei, Yunxiao Co., Zhangzhou Prefecture, Fujian Province, China.

4th Oct 2016 16:05 BSTPavel Kartashov Manager

These are yearlier rosettes of green siderophyllite overgrown by later muscovite - very often they are still green and coarse granular inside.

5th Oct 2016 15:25 BSTDan Costian

Thank you, Pavel.

5th Oct 2016 16:04 BSTDan Costian

Calcite pseudomorph after Douvilleiceras ammonite from Tuléar Province, Madagascar.

6th Oct 2016 13:36 BSTHarold Moritz Expert

Muscovite ps. after schorl from a couple of places in New England pegmatites.

First a gallery of them from Noyes Mt. Quarry, Greenwood, Maine:

Another muscovite gallery with several examples, some partial replacements, Nathan Hall Quarry, E. Hampton, Conn.:

6th Oct 2016 21:51 BSTDan Costian

Siderite pseudomorph after scalenohedral calcite (aka Lady's slippers).

From Turț Mine, Turț, Negrești-Oaș, Oaș Mts, Satu Mare, Satu Mare Co., Romania.

7th Oct 2016 15:11 BSTDan Costian

Descloizite pseudomorph after vanadinite. From Touissit, Touissit District, Jerada Province, Oriental Region, Morocco.

8th Oct 2016 04:31 BSTJohn Christian

T. Douglas Schonewald Wrote:


> Chalcedony replacing snail shells.


These five shells are not pseudomorphs; they are internal molds made of chalcedony that filled the hollow space in the shells. The chalcedony shows none of the exterior texture of the shell. White traces of the original carbonate shell may be present between the whorls.

Here are quartz casts (pseudomorphs) of brachiopods found in limestone from the Devonian Martin Formation in central Arizona. Note that you can see the texture of the surfaces of the original shell.


8th Oct 2016 08:44 BSTGianfranco Ciccolini

Pseudomorphous aggregate of phlogopite, composed of small dark brown pseudohexagonal crystals, after possible pyroxene crystal: . This type of pseudomorphism is not uncommon in volcanic projectiles, such as that of the Lake Vico area, specifically in Tre Croci, Vetralla, Viterbo Province, Latium, Italy.

8th Oct 2016 14:28 BSTRolf Luetcke Expert



Often I have found pseudomorphs but they are after an unknown mineral. Here are a couple of examples. The first one I found at a small prospect in SE Arizona. I didn't find any of the crystals that had not altered so have no idea what the original mineral was.

The second photo is also from Arizona, Ray mine but again, never found the original unaltered to say what the original mineral was.

I have been enjoying seeing all your posts, so many great pseudos out there.


8th Oct 2016 17:01 BSTDan Costian

Calcite pseudomorph after a hoppered glauberite crystal group from Camp Verde Salt Mine, Camp Verde, Camp Verde District, Yavapai Co., Arizona.

9th Oct 2016 14:13 BSTDan Costian

Chalcedony pseudomorph after baryte from Henry Mts, Garfield Co., Utah.

9th Oct 2016 14:39 BSTAndy Young

Quartz after gypsum? Let me know if you want to revise that. Found at Starved Rock Clay Products, Illinois. Pennsylvanian, Illinois basin.


9th Oct 2016 15:25 BSTHarold Moritz Expert

Andy, interesting, is the pseudo the whole piece of just the corner with the concentric features? That area looks like a stromatolite.

Among the many pseudomorphs found at the Tilly Foster Iron Mine near Brewster, NY:

Antigorite after chondrodite:

Antigorite after dolomite:

Lizardite after amphibole?:

Lizardite after chondrodite:

9th Oct 2016 18:07 BSTNorman King Expert

OK, here I go again.

Dan Costian (October 05, 2016 04:04PM) shows an ammonite where you can clearly see the original beige aragonitic shell material. The brown material below that was the open space where the animal lived, or where gas had accumulated in the shell behind the “living chamber" to make the shell buoyant. That’s where the calcite precipitated. Thus, this is a calcitic internal mold, not a pseudomorph. However, it may be that the shell material is also calcite now, in which case it has indeed pseudomorphed the original aragonite of the shell. But the calcitic cavity filling is just that-it "replaced" air or water, not mineral matter.

The photo in a posting by John Christian (October 08, 2016 04:31AM) includes snail shells from this thread that I also used to point out the issue (September 10, 2016 04:48PM). Then John posted real pseudomorphs showing the external features of brachiopod shells. This is silicified calcitic shell material (not aragonitic, as it was for both the snails and cephalopods), and that’s why the external features of the shells are preserved. This preservation mode is very common in fossils in Paleozoic carbonates that are partially to completely silicified. He is correct in referring to those as pseudomorphs. In paleontology, we would call that preservation mode “replacement,” however we would see nothing wrong with using the term pseudomorph.

Guys and gals, I really don’t care if mineral people are not concerned about getting this right, but if anyone does care, I could write up an illustrated discussion of the situation. However, I don’t want to waste my time if it seems unimportant at Mindat. I have noticed this misconception seems to permeate the examples illustrated here, and examples that are being offered for sale in the mineral-collecting world. Such entrenchment suggests it may be a hopeless campaign that would not be worth a paleontologist’s (or sedimentologist’s!) time.

9th Oct 2016 18:29 BSTAndy Young

Harold, the tan mineral on the concentric form is quartz of some kind. I haven't done any tests yet, so I don't know whether the dark concentric forms are matrix cast with the original or whether they are darker quartz or another mineral altogether! The paleontologists on site were quite sure the "blossom" was mineral originally, gypsum maybe.


9th Oct 2016 18:39 BSTAndy Young

Norman, sorry to get you riled up, not my intention. As a novice, I will try to stay clear of the more "scientific" threads if I can! But hear me out, I was thoughtful about whether to put this on the ID thread or this one, and the reason I did was this: this was collected with an earth science club, and the group was predominately fossil bent. Several paleontologists thought the form was a gypsum rose and not organic in origin. Thus, I was under the assumption that the quartz had replaced the original mineral. Cheers!


9th Oct 2016 19:13 BSTNorman King Expert


Don't worry, I was not referring to the gypsum/quartz situation. I guess I sounded a bit off-put, but only because we have discussed pseudomorphed fossils before, and my complaints seemed to generate caricatures of the issue.

Is gypsum found at the clay quarry? I've worked on Pennsylvanian beds in the Illinois basin, and haven't run into that. That apparent fossil is interesting. Harold suggested it looks likes a stromatolite, but a stromatolite would be a whole pile of laminations that built up vertically and would not likely be in a gypsum deposit. Gypsum suggest a quiet-water environment whereas stromatolites form in agitated water. I haven't seen anything quite like what you show.

Keep at it!

11th Oct 2016 18:24 BSTDon Saathoff Expert


In August of 1998 Ray DeMark opened a pocket in an extension of the Sunshine #4 tunnel of the Blanchard Mine which contained these malachite pseudomorphs of linarite. No more have been found other than those specimens removed from that pocket. He gifted this specimen to Cookie & me later in '98. Some of the pseudos still had a core of linarite.

Don S.

11th Oct 2016 18:53 BSTHarold Moritz Expert

Kyanite pseudomorphed by very fine grained muscovite:

12th Oct 2016 02:49 BSTRolf Luetcke Expert


I am still working with our gold sub collection and came across this one I purchased a while ago. It is from Cripple Creek Colorado and a gold pseudomorph after calaverite.

12th Oct 2016 07:50 BSTJohn Christian

Norman King [ PM ]

Re: Pseudomorphs

September 10, 2016 04:48PM

“On the mindat gallery for agatized corals (, none of the fine skeletal structure of the corals is preserved, and they are actually neither molds nor casts.”

I looked at three photos on mindat that Norman mentioned in an excerpt of his September 10th post above. I think that all three photos of coral show traces of the exterior of a coral including broken exteriors of a coral. These and other Tampa Bay “agatized corals” that I’ve seen should be called fossil casts (and therefore pseudomorphs) as long as some of the exterior texture of the coral is present.

Here is a brief paleontological definition of a mold. A mold is the material pressed or formed against an organic part of an organism to be fossilized. In the case of the Tampa Bay coral, the sediment on the outside of the coral became an external mold. An internal mold is the sediment pressed or formed against the interior of an organic part of an organism. The snails that were replaced by chalcedony are interior molds.

Paleontologically, a cast is made by forming or pressing a material against a mold. The coral dissolved away leaving an exterior mold. Chalcedony partially filled the mold and become a cast, albeit a very crude and imperfect cast. The chalcedony cast does retain some of the original exterior texture of the coral. Thus, it is proper to call the whole chalcedony mass a cast and hence a pseudomorph. Even a partial cast is a pseudomorph.

12th Oct 2016 13:29 BSTHarold Moritz Expert

Diopside pseudomorphed by tremolite, in parallel growth. These were initially named "canaanite" after the Connecticut town, which is still a handy term in conversation compared to the technically correct mouthful. They are common in the Cambro-Ordovician Stockbridge/Inwood Marble.

12th Oct 2016 15:03 BSTNorman King Expert


The issue of semantics comes up here, and it shows that paleontological terms cannot be transferred well to mineralogy, and vice versa.

The corals shown in are colonial organisms, and the interior of the coral structures actually consisted originally of hundreds of individual animals, whose skeletons were not distinctly separated from the others. Each of those individual skeletons (“thecae”) has disappeared. Note also that individual thecae may be separated from others by extra-thecal skeletal material collectively referred to as “coenosteum.” There are no internal or external surfaces against which a mold could be made or which could confine the distribution of poured-in material for the making of a cast. You cannot have a cast unless those surfaces are present.

The question of what we are trying to mold is also critical here. The coral colony (“corallum”) takes whatever shape is imposed upon it by the immediate environment, involving currents and exposure to wave action (and breakage by same), as well as impingement on the growth of the members of adjacent colonies; what remains after being consumed by coral-eating fish is also an issue. Whole colonies tend to grow upward (but not substantially above sea level), but budding may occur to expand their horizontal reach. Colony form is also restricted by adjacent members of the corallum, and there is no set exterior form. The situation is somewhat like the difference between making a cast of a vase or a bust of Abraham Lincoln in ceramics class, or just letting the plaster plop onto the floor and make a shapeless blob. No, the mineral objects we are referring to here are neither casts nor molds.

Other colonial organisms (e.g., sponges and calcareous algae) have similar issues. By comparison, snails and brachiopods are easy. I tried to make allowances for some of the corals. however.

Next is the issue of what is a pseudomorph. I don’t know the history of the term very well, but I am sure that at one time the term had a more precise meaning that was fairly restricted in scope. A pseudomorph was a mineral material that replaced a previous one, mimicking the characteristic habit (e.g. crystal form) of that earlier mineral, but the composition and atomic structure of the new mineral didn’t match what the original mineral had. OK, then what do we mimic in the coral? The crystal habit of aragonite? (It would be calcite for ancient corals.) No–that’s not it. There is no aragonite or calcite habit that is being mimicked. This is a big problem in using the term for fossilized skeletal (mineral) materials. And, with time and use of the term “pseudomorph” by mineralogists for more and more things, the term has become so broad that you may no longer know precisely what is being discussed when you read or speak it. Of course, that is a problem with the meanings of nearly all words–the definitions get broader with time, since definitions of words reflect the way words are used (and misused!), rather than some original, precisely defined meaning. After a while, a complex history may have developed, and we are seeing this right now in trying to extend the term pseudomorph to fossils. In paleontology, however, we do have very precise meanings for both morphological terms and taxonomic names, and you have to go back to older literature to see what the meaning of a term is.

The best solution to this matter, insofar as corals and other colonial marine animals and plants (OK, photosynthesizers for you purists) are concerned, is not to refer to them as pseudomorphs. Also, we should use the terms mold and cast properly.

12th Oct 2016 15:40 BSTAlfred L. Ostrander

Hello Everyone!

Your obnoxious pedant checking in here. Everyone should read the posting Misuse of term "Pseodomorph" posted by none other than Jolyon under the Maintenance >Mistakes thread. Early in this thread I posted my thoughts on what a pseudomorph is or isn't, if you will. Jolyon, et al have posted their concerns in the thread I have brought up here. By Jolyon's preferred usages, a lot of postings here don't cut it. I am of the opinion that everyone read Jolyon's posting. Much of it lines up with what I was taught in college mineralogy and paleontology classes. There are also some interesting historical and present usage discussions to help those who are interested.

Best Regards,

Al O

12th Oct 2016 19:41 BSTJohn Christian

Thanks Alfred for pointing out Jolyon's article. It is worth reading.

Paleontologically, the Tampa Bay corals can be called replacements or casts since they preserve part of the exterior (no matter how chewed up). The term cast also applied to fossils that are replaced bit by bit by another material. The mold does not have to be empty before a cast is created. I used or misused the term pseumorph (as others were trying to use it earlier in the posts) as applied to fossils. The term pseudomorph is rarely used in paleontology. Replacement and cast are the preferred terms.

Here is a silicified cast of a coral in the same rocks as the silicified brachiopods that I posted earlier. These casts sometimes have hollow centers with a few crystals. They don't have the nice chalcedony that the Tampa Bay ones have.

From now on I (we) shouldn't post any more fossils and refer to them as pseudomophs in a thread about mineral pseudomorphs. :-)

13th Oct 2016 17:59 BSTDan Costian

Chisel-terminated crystal of danburite entirely covered (pseudomorphed?) by calcite.

From Charcas, Mun. de Charcas, San Luis Potosí, Mexico.

15th Oct 2016 01:03 BSTAlex Earl Expert

Here is an interesting one that I collected, it is what I think is Goethite (may even be Acanthite, or another silver mineral), which has pseudomorphed after a Bromargyrite octahedron modified by a cube. There are still some unaltered crystals on the piece.

This is from the lower D site Dumps, at the Blue Bell Mine, California

18th Oct 2016 21:22 BSTDan Costian

Druzy quartz partly coating/pseudomorphing fluorite from Wenshan Autonomous Prefecture, Yunnan Province, China.

18th Oct 2016 21:49 BSTAlfred L. Ostrander


Is the quartz actuallly replacing any of the fluorite? I am struggling with the concept that one mineral forming on another is truly a pseudomorph. I see this as an association but nothing that makes it a pseudomorph. Is there any information I am missing?

Best Regards,

Al O

18th Oct 2016 22:10 BSTHarold Moritz Expert

While searching all mindat ferberite photos recently, I came across six other places where that mineral pseudomorphs scheelite, like those I've already posted from Trumbull, Conn. Japan Congo France Rwanda England England

18th Oct 2016 22:48 BSTAndrew Debnam

Hi Al, Not a Pseudo in my humble opinion. More of secondary over growth of quartz but I do not see this a replacement of Fluorite. This is a common association in many localities.

Such as Riemvasmaak South Africa. Dealers actually remove the quartz coating to expose the Fluorite.

20th Oct 2016 18:13 BSTJyrki Autio

From Finnish pegmatite: Soft and green, probably chlorite pseudomorphs after unknown gadolinite. About 1 cm in size. They are formed perpendicular to biotite layer (like eg. Ytterby fergusonite) I have about dozen of similar ones, so these two are not accidental but typical for locality.

Something unusual or usual?

10th Nov 2016 12:31 GMTRolf Luetcke Expert


This is one I photographed just a couple of days ago. The piece is self collected in the pit at the Morenci mine when they were still doing collecting tours. Nice, sharp replacements of limonite after calcite.

10th Nov 2016 12:35 GMTRolf Luetcke Expert


This one is quite unusual and one we bought from Jaroslav Hyrsl a while back. It is a hellyerite pseudomorph after millerite. The millerite has been completely replaced. It is not pretty but an unusual one.

Thanks all for posting so many great photos of pseudos and quasi pseudos on a thread I have loved looking at all your photos.

10th Nov 2016 12:43 GMTHarold Moritz Expert

Fahlunite pseudomorph after cordierite. They were common at this location (they've been dug for ~175 years!), but this one from an old collection is very good, see all 3 views.

10th Nov 2016 14:45 GMTPavel Kartashov Manager

Rolf Luetcke Wrote:


> It is a hellyerite

> pseudomorph after millerite. The millerite has

> been completely replaced. It is not pretty but

> an unusual one.

This hellyerite itself is on the way to zaratite.;-):-D Real fresh helyerite is light blue. So probably soon you will obtain ternary pseudomorphose.

10th Nov 2016 17:05 GMTRolf Luetcke Expert


Funny how that goes, will have to keep that in mind. Of course many minerals are in transition, hope this one not as fast.

One specimen a friend gave me from the US that when I looked it up on mindat it said the mineral looses water so fast that the only way the species can be photographed is in situ in the mine, just carrying it out it alters. Can't off hand recall which one it was but that description was on the site and the fellow who sent me the piece was not even aware of it.

Thanks for the heads up.


11th Nov 2016 00:57 GMTPavel Kartashov Manager


you never work with tolbachite!:-D It transforms into eriochalcite during seconds, right on its way from box to another box. You take transparent orange-red sharp crystal and put dull bluish-grey not so sharp, swelled grain. Air moisture is enough for transformation. By the way in the same room villiaumite was stored more than 35 years without any alteration into thermonatrite. In this room was really dry air!

11th Nov 2016 01:06 GMTPavel Kartashov Manager

In time of my childhood (I don't know how it is now) many collectors supposed these silky grey grains in juvit-pegmatites delkhaielite - / &

But in reality they are fibrous pectolite pseudomorphoses after massive delkhaielite grains.

11th Nov 2016 16:52 GMTTony Albini

Two more nice "wolframite" (ferberite) pseudomorphs after scheelite from Trumbull, CT can be seen on my user's page. Also, at Trumbull partial replacements where the ferberite started to replace the scheelite were often found with most of the scheelite still untouched..

Other Connecticut items include bertrandite after beryl from the Biermann Quarry in Bethel, CT and bavenite after beryl from the Slocum quarry in East Hampton, CT. One bertrandite pseudomorph was 10 inches long! At one granite pegmatite in Ct, I collected lepidolite, albite ,and quartz after elbaite. Three replacements at one quarry after the same mineral!

In Utah, I field collected hematite after garnet in the Pismire Wash, Juab Co., Utah. I will try to get photos of these in the future.

11th Nov 2016 17:27 GMTRolf Luetcke Expert


Looked it up and although chalcanthite changes, sometimes rapidly, it was not the mineral I was thinking of.

The mineral is switzerite, which changes so quickly to metaswitzerite it doesn't even have a photo and the mindat page for switzerite tells why, very interesting to read.


11th Nov 2016 23:30 GMTFlavio Simon

The definition of Pseudomorph in my Glossary of Geology, second printing 1973, copyright American Geological Institute is very simple and easy to apply. I see that the the latest edition of the Glossary of Geology is its 5th edition published in 2011 - I wonder if the Pseudomorph definition has changed. Cheers!


14th Nov 2016 12:09 GMTDale Foster Expert

Harold Moritz Wrote:


While searching all mindat ferberite photos recently, I came across six other places where that mineral pseudomorphs scheelite, like those I've already posted from Trumbull, Conn. Japan Congo France Rwanda England England

Here is a seventh location:

Wolframite pseudomorph after Scheelite from Cligga Mine, Perranporth - a 7mm, very rough octahedral pseudomorph in the centre of view, there are also a number of smaller but much sharper pseudomorphs on the specimen but my current photography set-up is not up to capturing a decent image of them yet. Considering it had been sitting exposed on the dump for a number of years it is still in reasonable condition.

The octahedral shape is more readily visible in these views.

Not a great picture, but shows one of the smaller, sharper pseudomorphs.

15th Nov 2016 07:19 GMTChristian Auer Expert

A pseudomorph that you`ll probably don`t see very often and that I collected this year:

Cinnabar after chalcopyrite

15th Nov 2016 07:32 GMTPavel Kartashov Manager

Dear Christian,

according to colour, transparency and cleavage on breaks this is rather pseudotetrahedral xls of primary cinnabar rather than its pseudomorphoses after chalcopyrite or sphalerite.

15th Nov 2016 11:32 GMTChristian Auer Expert

Pavel, thanks for your input! Yes that mine produced a lot of strange cinnabar like this one

These xtls on the picture mentioned are running under pseudo`s since around 1980 in many collections. Here is another one

I have been wondering a long time if they are pseudos or not and if then after which species.

You can find there plenty of tiny chalcopyrite xtls spread over dolomite (SEM-EDS analysed) and even more darkbrown ones which are already limonite.

You find also some sharp terminated xtls part cinnabar part limonite.

I for myself cannot say for 100% sure the xtls on the pic are pseudos but I would be happy to get more opinions on them!

Got an PM before mentioning metacinnabar in any way ...

15th Nov 2016 14:18 GMTRolf Luetcke Expert




Very cool photo and of such an unusual replacement.


I think I saw with Christian what I have found at small mines in Arizona that have a lot of alteration taking place. Chris mentioned his looking at a lot of specimens from that location and found partial replacement that seemed to show what was going on. I have found the same with specimens I have from places I have collected, it can often take a long time looking at hundreds of specimens before the proper alteration falls into place. At first you wonder what is going on and then find another piece of the puzzle, then another and finally the photo comes into view.

As for the tolbachite you mentioned, yes, some from the volcano there are tough to keep. I have quite a number since they are often copper related species, a mineral I like to collect. Unfortunately they are often in sealed containers. Even then a friend had a specimen from there he said he watched change while studying the piece under the microscope. Many of those are really cool species but not easy to have in a collection, especially in a damp climate. Our Arizona dry climate has kept them in better condition but as you mentioned a couple of posts back, some are in the process of altering.

The two photos here are of massicot, often replacing other species. In this case I don't have enough material to know just what mineral they replaced, guesses maybe but no positive idea.

Thank you all for posting your great specimens on this little thread.


15th Nov 2016 14:36 GMTHarold Moritz Expert

This specimen, which I purchased from a dealer, is labelled as goethite pseudomorphous after chalcopyrite. It is clearly a pseudomorph as the preserved external crystal form and habit are not correct for goethite and broken portions show a fine-grained interior. The original crystals do show a tetragonal symmetry, but not the typical disphenoid (pseudo-tetrahedral) form shown by chalcopyrite, but that mineral can exhibit other forms also. The white matrix is marble and the aggregate is plausible for chalcopyrite and its chemistry is more likely to be replaced by goethite than if the progenitor where say a silicate. There are only so many candidate minerals in the local marble where this is supposedly from, and chalcopyrite does appear most likely. Though if so it would have been a very well crystallized chalcopyrite for Connecticut. Perhaps it is really from the French Creek, PA area? Check out all the photos.

15th Nov 2016 17:16 GMTPavel Kartashov Manager

This is pseudomorphose after pyrite. If it would be chalcopirite, green malchite films would grow over marble matrix. There aren't any secondary copper mineral in the field of view.

15th Nov 2016 18:47 GMTHarold Moritz Expert


That could be correct, but the pyrite crystals would be rather distorted. I will look at the piece again carefully and see.


16th Nov 2016 16:18 GMTPavel Kartashov Manager

Until very recently I believed that copper pseudomorphoses after aragonite are massive and complete. Today I received one of them and was very surprised its small weight. Under binocular I discovered thad copper layer is very thin and under it is translucent aragonite core. In other words these pseudomorphoses in reality are copper foil over aragonite crystal. If anybody will dissolve aragonite he will obtain empty copper shell with walls less than 0.5 mm.

Frankly speaking I was very dissapointed in these samples. I was hoping to get the massive copper nut.



Are all these pseudomorphoses only copper-coated and in reality are aragonite inside?

And what about famous cassiterite pseudomorphoses after orthoclase? Are they also orthoclase crystals with only thin cassiterite film over feldspar core?

16th Nov 2016 18:35 GMTReiner Mielke Expert

Hello Harold,

Looks to me like maybe after marcasite.

16th Nov 2016 22:44 GMTAlex Homenuke Expert

Hi Pavel,

Here are 3 "pseudos"

The one on the left, I cut open - about 10% copper by volume. The one in the middle was leached to remove the aragonite - about 50% copper by volume. The one on the right by the feel is about 90% copper (purchased from Alfredo by the way)

16th Nov 2016 23:07 GMTGreg Dainty

Chrysocolla psudo sampleite, E26 Pit, Northparkes mine, Parkes, NSW. size is 38 x 22 x 22mm. Identified by and from the collection of Jim Sharpe

17th Nov 2016 06:52 GMTDale Foster Expert

Pavel Kartashov Wrote:


And what about famous cassiterite pseudomorphoses after orthoclase? Are they also orthoclase crystals with only thin cassiterite film over feldspar core?

The Wheal Coates pseudomorphs can vary in the degree of replacement of the feldspar, but those that are full replacements are Cassiterite all the way through. The weight of the specimens indicate that they are full replacements.

This example is predominantly Cassiterite with a minority of Quartz grains.

This example from Wheal Bungay, which lies adjacent Wheal Coates, shows full replacement of the orthoclase but is contained within it original host rock, unlike the majority of the Wheal Coates pieces.

17th Nov 2016 12:52 GMTPaul Nicholson Expert

If you can excuse the quality of the photos, I'd like to share this one. I collected this in March 1999 underground at Wheal Gorland from a small area in the level just above the main collecting area in Davys stope. There was only supposed to be pharmacosiderite in this cavity so I was suprised to discover this once I started to go through my finds at home. Unfortunately I only have two of these but they appear to be pseudomorphs of pharmacosiderite after chalcophyllite. Field of view on the first one is about 4mm.


17th Nov 2016 13:14 GMTHarold Moritz Expert

Reiner: I will look into that suggestion, thanks.

Alex: Begs the questions, "partial replacements?" or "intergrowths?"

Dale: Those are some weird pseudos!

Greg and Paul: Beautiful and fun stuff.

The wonders of the mineral world seem boundless!

18th Nov 2016 02:22 GMTHoward Heitner

One of the great unknowns in understanding pseudomorphs is how one mineral replaces another with no similarity in composition. One example is copper after aragonite. Some possible mechanisms are presented in a paper by H. Strunz, Aufschluss 33, 313-342 (1982) His title is Pseudomorphosen- Der derzeitige Kenntnisstand.Versuch einer Klassifizierung

18th Nov 2016 22:49 GMTRolf Luetcke Expert


That is the kind of pseudo I love finding, a total surprise. I had just found the massicot after in a couple what looked like jarosite was the original mineral. I have seen them after cerussite but the following after what looked like jarosite was new to me.

Loved you posting Paul.

In fact, love all the fine postings.


21st Nov 2016 00:27 GMTRolf Luetcke Expert


These are odd little pieces from the Majuba Hill Mine in Nevada. Many are completely replaced azurite by the cornubite and in this case there are some with azurite still at the core. Many are translucent green with no azurite left.

22nd Nov 2016 18:14 GMTPavel Kartashov Manager

Partial pseudomorphoses after rhomb-like crystals of Schreyerite in mica shist from Srednyaya Padma deposit in Central Karelia. You may to see black relicts of Schreyerite within light masses of secondary Roscoelite and Rutile.



FOV size of pictures A2 and B is 12 mm. Cut unpolished surface of the rock.

28th Nov 2016 22:57 GMTRolf Luetcke Expert


I came across this one today while looking at spangolite from the Mex-Tex Mine. This is a malachite which I first thought was coating a tabular crystal but on one edge, from a different angle, it is a complete replacement so a pseudomorph. Only question is which mineral it replaced. Most common tabular mineral from this mine is baryte but I had not seen a malachite after baryte before. Strange crystal.

29th Nov 2016 14:52 GMTRolf Luetcke Expert


I was thinking about the malachite and baryte situation and remembered I had a piece a friend gave me from Zaire a number of years ago that is malachite and baryte mixed together, not a replacement but it does answer my own question if baryte can be replaced by malachite, apparently it does happen.

Wanted to thank all those posting on the pseudomorph thread, I have been enjoying all your posts.


29th Nov 2016 15:53 GMTRolf Luetcke Expert

Addendum to first photo. I took the piece out again and although there is malachite, tested with effervescence with HCL, a small piece of this material showed only minor bubbling so although the one test was malachite, this pseudomorph is brochantite according to the acid test. Still an odd situation on this one specimen.

16th Dec 2016 21:13 GMTRolf Luetcke Expert


Came across this piece today. It is from the 79 mine in Gila County Arizona. It is mostly of hemimorphite but with it were a couple of replacements. The original mineral replaced was calcite but two things seemed to have taken place. They were first replaced by the iron oxides, dark probably hematite at the top and yellow probable limonite in the center but then there was something else that happened and quartz coated them and the inner material was lost and the quartz epimorph was left. The hemimorphite here was also totally coated by quartz. Lots of alteration in this piece.

16th Dec 2016 23:42 GMTRichard Gunter Expert

Hi Rolf:

Your scalenohedrons might be Smithsonite instead of Calcite. Altering Smithsonite occurs at the 79 Mine and it can be followed by Hemimorphite. The last phase on my samples is Chrysocolla rather than Quartz. You are correct that the 79 Mine paragenesis has a lot of alteration and many pseudomorphs.
I stretch it maybe a little bit far, since this is not really a pseudomorfose, but rather a perimorfose.

It is still a mystery what the original mineral may have been. There is a possibility it once was laumontite, while others have suggested scapolite.

Anyway, what can be observed is that these tube-like structures have a rectangular crosscut, and I have observed some with a inclined endplane like what is normal for laumontite. Though they are very coarse, and it might be that the endplanes are just very distorted into one direction due to some form of directional crystallisation.

Any suggestions based upon the fact that this is a granite pegmatite?

The pink and off-white/yellowish mineral is microcline, associated with a green powderish chlorite mineral.

Sorry, I don't have time to make a better picture right now. I will post plenty of new pictures for the Landsverk 1 quarry, Evje, Norway in the spring of 2017. A better picture of this material will be amongst them.

Ron Werner


17th Dec 2016 12:53 GMTHarold Moritz Expert

Laumontite and scapolite would be very strange for a pegmatite. What is the mineral doing the replacing? Is this pegmatite Li enriched? I am guessing fine-grained muscovite replacement of spodumene? A common thing here in New England.
No, Li is very rare in the pegmatites of Evje-Iveland. Spodumene has not yet been found here at all.

The Landsverk 1 pegmatite is pretty unusual with three different stages: magmatic, metasomatic and hydrothermal.

Zeolites found here are: analcime, chabazite and stilbite.

Another unusual paragenesis in a nearby pegmatite (1.22 km S of Landsverk 1) was in the Åneland 2 quarry (Smænelia), where a pseudomorphose of sillimanite after probably andalusite was found, together with tiny corundum crystals (sapphire!) and anhedral diaspore. This excess of aluminum is not reflected by the chemistry of the bedrock.

(Larsen, A.O., Kjærnet, T., Kihle, J.b. & Werner, R. (2015): Sillimanite in a granite pegmatite at Evje, Aust-Agder. Norsk Mineralsymposium 2015, 37-43.)

17th Dec 2016 16:10 GMTHarold Moritz Expert

Wow, those are weird pegs. OK, then in your photo, I think the laumontite is plausible.

20th Dec 2016 13:27 GMTRolf Luetcke Expert


I think you may be right about it being smithsonite but none is left on the specimen that tells the "whole" story. I do have a number of pieces from this mine and lots and lots of alteration. The final coating is of tiny, druzy quartz and if there is color of light blue, it could be chrysocolla since that is often on these pieces also. There is rosasite on them also and since it is covered completely it is hard to tell. Druzy quartz doesn't allow for one to see what is underneath unless one has a broken surface close by.

One fellow told me one time that the coated crystals were gypsum but I took another look at what he thought and it was hemimorphite after all. Can't always believe what people tell you and this fellow said he worked at a university. Well, he needed to take another look again too. Never did see him to discuss the situation.

Great to see a few more posts on the thread, love all the photos and the nice thing, it is a great learning experience too.

18th Jan 2017 16:37 GMTDennis McCoy

Here is an antique Limonite Pseudomorph of Siderite, with the original label from Hans Jaklin.



18th Jan 2017 17:45 GMTRichard Gunter Expert

Hi Rolf:

Have you every seen Willemite on your 79 Mine samples? There is so much mobile copper in the system that there may be no green fluorescence but some of my "Hemimorphite" looks like they were hexagonal plates before they were covered by Chrysocolla.

30th Jan 2017 21:06 GMTRolf Luetcke Expert

W. Richard,

Thanks for the suggestion about the Willemite, will look again. I do think it is hemimorphite, that is the most common on most of the specimens I have.

This is one I came across yesterday while splitting some massive jarosite I had. Inside were these pseudomorphs of jarosite replacing the original pyrite. Some of the material I had found was black with hematite after the pyrite but these, and there were broken ones to show the whole thing, had been replaced completely by the jarosite.

30th Jan 2017 23:14 GMTRichard Gunter Expert

Hi Rolf:

The sample in question has at least two separate generations of Hemimorphite separated by a coating of Chrysocolla. I have seen only one other sample like this. In the E-minerals database on the 79 Mine there is an almost identical sample with the two generations of Hemimorphite and a note saying it was collected by Richard Barstow in the early 1980's (mine predates 1976) so they are fairly rare and older.

31st Jan 2017 02:36 GMTRolf Luetcke Expert

W. Richard,

I was looking at the photo again today and went to my collection drawer but the particular one is not in there. I have several places it could be and I have to check to see if I can find the piece.

I got my 79 mine material from half a dozen places over time. One was Harold Urish, we visited him often and I got things from him a number of years ago. The piece may be from him but I am not sure. Another source is a friend who collected there too and it could be from him. Some more recent material came from one of the partners in the mine in a trade. If I find the piece I can give more information. I agree with the two generations since some are coated and some not, I did find that interesting.

I let you know if I do locate the piece. My wife thinks my filing system is not the best but I do have about 4 sub collections, locality, micro, reference and display.

Didn't realize it was a bit more special, thanks.

7th Feb 2017 01:27 GMTRolf Luetcke Expert


Going through some 79 mine Arizona material I came across this quartz pseudomorph after wulfenite. There were others that were partly replaced and some with only a quartz coating but this one was completely replaced by the quartz.

11th Feb 2017 23:45 GMTRolf Luetcke Expert


This is a new piece we got for our collection at Tucson.

The malachite after azurite is as sharp as I have seen them, great luster.

Thanks Jimmie!!


12th Feb 2017 00:42 GMTSteve Sorrell Expert

For those on Facebook, there is also a pseudomorphs page - All welcome!



13th Feb 2017 16:22 GMTRolf Luetcke Expert


Doing a bit of research after I noticed the pyramidal shape that the cuprotungstite is not naturally this size and shape and the piece is probably a pseudomorph of the cuprotungstite after scheelite. Can't be sure but it is the assumption I am making here.

13th Feb 2017 16:52 GMTHarold Moritz Expert


The "malachite after azurite" above looks like azurite after dolomite or siderite. It appears to be an aggregate of rhombohedral crystals that those two minerals typically form. I dont know a ton about Milpillas, but I see neither of those two minerals listed there on mindat, nor any photos that look like yours for azurite or malachite. Perhaps not from there...

14th Feb 2017 00:05 GMTHoward Heitner

There is one pseudomorph that started to bother me recently The well known "copper after azurite" from Georgetown, NM. called "roses". My specimen did not conduct electricity and had a density of 3.4 (copper 8.9) I found a reference (T. A. Hanson, Copper Roses from the Rose Mine, Min. Rec. May-June, 195-202, 1994).discussing among other things the formation of the "roses" Hanson gives a chemical reaction showing aqueous Ca+2 reacting with azurite to form copper and calcite. He states the average density of the "roses " is 3.9 which works out to 44% copper by weight. So really the pseudomorphs should be called copper/calcite after azurite. Since the copper is dispersed in the calcite, the specimens do not conduct electricity. Therefore a lot of labels need to be changed in my opinion.

I do not fully agree with Hanson's chemistry however. I see Ca+2 reacting with the carbonate in azurite to form calcite.

I totally disagree with the oxidation of water by Cu+2 to form oxygen, copper and H+

2 Cu+2 + 2 H2O to 2 Cu (metal) + O2 + 4 H+

Any geochemists think that this can happen?

14th Feb 2017 00:34 GMTRolf Luetcke Expert



It is 100% a Milpillas piece, know the person I got it from like a brother, in fact I was the one that got them the original purchase from the mine a number of years ago.

The photo here is the back of the piece.

I took a dozen photos of the piece to try and show the luster of the piece, hard to get. This angle showed it off nicely but it is easy to see on several of the angles it is malachite after azurite and in places it is not totally replaced on a side view and one can see some of the azurite in the crystals.

The piece was quite interesting and that was another reason I posted the photo.

14th Feb 2017 13:48 GMTHarold Moritz Expert

Hi Rolf:

There must be blue sky reflecting off the crystals in the first image! I guess the crystals are azurite terminations, which can look like the corners of flat rhombohedra...very nice!

13th Mar 2017 00:43 GMTRolf Luetcke Expert


This is one I came across today. It is a limonite pseudomorph after not only the cubic cuprite but also the elongated variety of cuprite called chalcotrichite. On the sides of the specimen it shows pretty much all limonite but a few tiny remnants of cuprite were still deep inside the limonite.

13th Mar 2017 00:48 GMTRolf Luetcke Expert


This one actually helped me identify stibnite from the Blue Nose Mine from the Patagonia mountains. There was question as to what the material was and all I had seen was a photo and it was hard to tell.

When a friend gave me an actual piece from the find I was able to see the black stibnite had been partly and in this photo nearly completely replaced by the antimony ochre. The antimony ochre used to be called stibiconite in the past but there is a question if it is that mineral so the antimony ochre is now the preferred usage.

The other minerals at the location don't go through this replacement so the alteration made the identification quite easy and allowed a new mineral to be added to the location.

Thank you to Ron for the specimen to work with.

13th Mar 2017 01:05 GMTDennis McCoy

This is a nice plate of Limonite replaced Pyrite cubes, from Los Arenales, Malagas, Spain.

overall size approx. 3"x2"x1"



21st Mar 2017 17:41 GMTRolf Luetcke Expert



Following your limonite pseudo, this one is a double replacement of limonite after the platy clusters of former lepidocrocite and the small rhombs of limonite after calcite.

21st Mar 2017 17:43 GMTRolf Luetcke Expert


This is a replacement of light blue chrysocolla after platy azurite crystals. A bit of the remaining azurite can be seen at the left.

This one is from the same Last Chance Mine as the previous post above.

22nd Mar 2017 18:28 GMTHoward Heitner

Following up on a recent message from Harold Moritz, I have in my collection this specimen. It has a painted on label "Reinite Uganda " An old Behier collection label says "Ferberite Uganda" A more recent dealer label add "Lake Kiwa" The Kirwa Mine, Kigezi Dist. Uganda is listed on Mindat with a picture of a ferberite after scheelite pseudomorph. This probably the locality for my specimen.

22nd Mar 2017 18:41 GMTHarold Moritz Expert

Very nice, Howard. Sure is a dead-ringer for Trumbull material, at least crystal-wise. The matrix is likely different. Another place for these pseudos I didnt know about.

24th Mar 2017 19:17 GMTHoward Heitner

I just did a calculation of the volume change going from scheelite to ferberite. Assuming 100% replacement of Ca by Fe(+2) I calculate that there would be a decrease in volume of 15%. That would make the pseudomorph porous and the apparent density lower than that of ferberite. If you have one with no matrix, I would like to know the density. The calculation of volume change for reaction pseudomorphs is based on the formula weight of both of the minerals (normalized to one metal atom if necessary) and and their densities.

24th Mar 2017 19:22 GMTAlfredo Petrov Manager

Indeed, Howard, all the ones I've personally seen of these pseudos (from Japan and Rwanda) have been granular in texture, and so presumably somewhat porous.

24th Mar 2017 21:40 GMTHarold Moritz Expert

Howard, I'll see about those densities, but most of the loose ones I have a rather small and will have to bring them to someone I know with sensitive equipment. The one problem is that many times the psuedos from Trumbull are not completely replaced, so there may be zone of unaltered scheelite inside. That said, here is one that I found with some voids in it (very rare) lined with tiny ferberite crystals, which shows that the replacements are fine-grained.

25th Mar 2017 15:41 GMTTony Albini

Hi Howard, I spent a lot of time at Trumbull, CT looking for pseudomorphs of "wolframite" (Ferberite) after Scheelite. Most were wholly replaced and heavy but I did see a few partially replaced, I have one TN piece where the front face is ferberite and the rest is scheelite. Also, the granular type material with voids was crudely crystallized. Ronald E. Januzzi had a chemical analysis done on what he called Spheroidal Ferberite, this was done at Grand Junction Laboratory, Grand Junction, Colorado by a chemist named Bower. The results were Tungsten, 60.1%, Iron, 17.8%, Manganese, 0.021%.

I would suggest you do a specific gravity. Richard Schooner had a very inexpensive device. for doing S. G. tests. The device worked very well.

How large is the specimen in your photo?

Regards, Tony

27th Apr 2017 01:33 BSTHarold Moritz Expert


I just got three 4 cm chunks of ferberite after scheelite from Trumbull for you to play with. Lemmeno if you still want some.

4th Jun 2017 13:25 BSTRolf Luetcke Expert


Just came across this piece, a complete replacement of hematite after calcite with groups of elongated goethite crystals from a small Unnamed Cu Prospect near Copperopolis in Yavapai Co. Arizona. This is material from a friend and I never did see any of the unaltered calcite crystals.

8th Jun 2017 23:47 BSTRolf Luetcke Expert


This piece came out from a find at Rowley a few years back. Some had nice crystals of minium after cerussite.

16th Aug 2017 22:49 BSTRolf Luetcke Expert


Came across this odd pseudomorph today in some material from a friend. It is limonite pseudomorphing marcasite on a quartz matrix.

17th Aug 2017 18:31 BSTScott Rider

Chalcedony after calcite; 08/2017 Found by myself on a camping trip to Houselog Creek, Saguache, Colorado.



17th Aug 2017 18:48 BSTScott Rider

One more from Houselog Creek... I like the contrast between the manganese colored pseudo's and the one clear one at the top. Some of the pseudo's found this year were up to 2 inches (not my find, but my buddies)... The pseudo's had two main forms, regular rhombic shapes and more rare, scalenohedral "dog tooth" crystals.

20th Aug 2017 13:30 BSTRolf Luetcke Expert


Cool piece. Love some of those odd things quartz can replace.

Thanks for posting those photos.

25th Aug 2017 00:00 BSTPavel Kartashov Manager

This is very rare case of complete and compact pseudomorphose of Wadeite after tabular Eudialyte crystal. Usually, due to great difference in zirconia contents in these two zirconosilicates, such pseudomorphoses are cavernous, but not in this case. Probably this crystal was joined with larger size eudialyte crystal and wadeite filled its volume completely during metasomatic replacement.



25th Aug 2017 00:09 BSTPavel Kartashov Manager

This is more abundant for the locality situation - dissolved Eudialyte grain with pinkish hexagonal tabular-bipyramidal crystals of free growth Wadeite of the 1st generation at walls of the cavity.


But at the side of the same specimen we can to see inclusions of colorless hexagonal fine-platy crystals of Wadeite of the 2nd generation in intergrowth with white Natrolite.

Apparently part of zirconium was mobile enough to escape from volume of replacing Eudialyte crystal in surrounding rock.

25th Aug 2017 00:10 BSTPavel Kartashov Manager

At this photo Wadeite-II xls are more better visible.

25th Aug 2017 14:43 BSTChris Rayburn

I couldn’t resist posting this. Limonite pseudomorph after pyrite, collected 21 August at Missouri Hill, Chaffee Co., Colorado. Yes, limonite ps. pyrite are a dime a dozen, and this one is ratty and far from perfect. What makes it notable (to me, anyway) is its size. It’s a single crystal that measures 19 x 17 x 16 cm and weighs just under 20 kg (44 lbs). I didn’t know they grow ‘em this big. My wife says it’s too ugly to be a yard rock. I have no idea what I’m going to do with the thing!

25th Aug 2017 15:02 BSTMatt Courville

Chris your pseudo is just awesome! I have an idea for you....get a few rock-hounding-like garden gnomes and have them protecting this in the garden like the Arkenstone - as a shrine;);)

25th Aug 2017 15:11 BSTWayne Corwin

I wonder if one that big is still pyrite in the middle?

25th Aug 2017 16:22 BSTDonald B Peck Expert


25th Aug 2017 17:21 BSTScott Rider

Wow, Chris, that is an amazing pseudo!!! That is such a weird coincidence... I was trying to get to Missouri hill from Mt. Shivano.. I was camping on Shivano about a week after you found that piece!! Just curious, is that a claimed area or is it just hard to find? I had very crappy instructions to get there and ended up going way out of my way and never found the spot LOL!

Edit-- after looking up the site in Mindat, I wish I saw that before I went to Shivano... Apparently there is a GPS to the spot, but I am not sure how close it is to the actual spot... I went up to Shivano not planning to go to MIssouri hill !!!

25th Aug 2017 20:12 BSTDennis McCoy

Don't know what to do with it? I'll take it off your hands!

26th Aug 2017 02:40 BSTRolf Luetcke Expert


Wow!! That is a whopper of a crystal. Would love to see a pyrite that size.

It should be kept whole and if not at your place, I am sure there are places that would love to have that. A museum would certainly love a pseudo. that size.

Glad you posted it.


26th Aug 2017 03:58 BSTKevin Conroy Expert

I wonder if the Colorado School of Mines Museum has one like this? If not, that would be a great home for it where lots of folks could enjoy it!

26th Aug 2017 12:18 BSTChris Rayburn

Thanks all. Wayne, I found a couple of dozen other pseudos ranging from 1-5 inches on an edge. Several of these came out broken, and a couple of them have relict pyrite cores. It wouldn't surprise me at all if this big guy does too.

Rolf and Kevin, you read my mind. I'd already toyed with the idea of waddling into the Colorado School of Mines Museum with this and gently setting it on Bruce Gellar's desk...

Scott, I'll PM you with site info.

27th Aug 2017 00:30 BSTAnthony Scoffler

If it isn't much of a burden, I wouldn't mind the site locality information for that either, Chris. Thanks for sharing.

It doesn't look like the Wheal Mary Ann quartz after fluorite pseudomorphs have been posted yet, so here are some.

There are many more among the locality's mineral pictures:

28th Aug 2017 16:11 BSTChris Rayburn

Hi Anthony--I'll send you a PM on this.

3rd Oct 2017 01:44 BSTRolf Luetcke Expert


This is one I am still working on. It is from the Ojuela Mine in Durango Mexico and I know the original mineral was cerussite but so far don't know what it was replaced by. If I find out I will post the mineral that replaces the cerussite.

3rd Oct 2017 03:28 BSTKevin Conroy Expert

These remind me of the goethite after selenites from Santa Eulalia.

3rd Oct 2017 13:18 BSTRolf Luetcke Expert


Here is another view of a different grouping. The first photo and this one both show twinning, typical of the cerussite I see. In the first photo is a nice twin at the bottom right and in this one at the left side is a twinned crystal. The association with the wulfenite and mimetite is right too for the cerussite. Don't know in this case what black mineral is replacing them. Goethite is a possibility but I know Ojuela has some odd black minerals that are there.


Thanks for your comment.

To me it reminded me of some coronadite after wulfenite I have from the Glove mine in Arizona.

This last photo is of the black with no seeming replacements going on.

29th Nov 2017 15:13 GMTDennis McCoy

A Tale of Two Epimorphs: It was the best of times, it was the...

What am I sayin’? It’s always the best of times when you collect two similar epimorphs from locations so far apart from each other. I just received this smithsonite epimorph after calcite, from Coldstone’s Quarry, UK. It is similar to the famous siderite/sphalerite epimorphs from Aggeneys Mine, North Cape Province, South Africa. The UK specimen is made up of smaller crystal shapes, but the underlying calcite crystal shapes are very similar. The Coldstone’s specimen is also more fragile.

The Aggeneys Mine specimen is quite empty of secondary growth. The Coldstone’s example is half filled with smithsonite and limonite globules.



29th Nov 2017 15:15 GMTDennis McCoy

A couple more photos:

Coldstone’s Quarry

Aggeneys Mine

30th Nov 2017 02:02 GMTHarold Moritz Expert

Very cool Dennis.

I just posted some similar pseudomorphs of prehnite after analcime here: and child photo

As the caption says, the analcime was first encrusted by secondary white prehnite and then naturally dissolved away. Then a further prehnite crystallization filled in the underlying void (some only partially). When the upper encrusting prehnite is removed it separates along the former analcime surface and reveals the "back side" of the latter void-filling silky prehnite below.

Here's another that is a complete replacement by prehnite after analcime:

30th Nov 2017 10:38 GMTHans Kloster

8 cm quartz ps after calcite from Minas Gerais, Brazil. Do You know where in MG it comes from? MG is big as France.


30th Nov 2017 12:26 GMTJohn Rakovan Manager

In case you are unaware but interested, a related thread that has been recently active is

When is a pseudomorph a pseudomorph?,11,425108,425536#msg-425536

30th Nov 2017 13:40 GMTHarold Moritz Expert

Roger that, John, I read that, very informative, thanks! I treat this forum as a place to post examples of pseudos because there does not seem to be a good place for them in "Best Minerals" and they are not easy to search for in the general database.

30th Nov 2017 13:42 GMTRolf Luetcke Expert



I have also been reading the other thread and am happy a few more have been posted to this one.

It has always been an interesting subject for me and the better understanding is great.

These two were in a box stored away some time ago. Re-found them and posted the photos.


30th Nov 2017 13:49 GMTHarold Moritz Expert

Hi Rolf. Is there a rhombic calcite cleavage or some way to identify it as calcite? I assume the hexagonal shape is from cyclic twinning of the aragonite. Obviously HCl will make both minerals fizz. A thin section viewed under cross-polars will show the calcite grains making up the pseudo.

30th Nov 2017 19:38 GMTRolf Luetcke Expert


I had posted the photos on the messageboard to question if anyone knew of these and a link took me to a paper done about just these pseudos. They even mentioned having them tested so I went with that information and posted the photos since they had been analyzed by people just from this location.

30th Nov 2017 20:50 GMTDennis McCoy

Rolph, I have a pseudo of aragonite that is almost identical to yours. Mine is from Texas, and is a chalcedony replacement. Do a scratch test on a broken edge to differentiate calcite/chalcedony. I have other, larger & smaller chalcedony replacements that are similar, but don’t have any locale info.

I’ve posted similar photos before, but here is a current one. Only three of these are still aragonite.

1st Dec 2017 12:44 GMTRolf Luetcke Expert


Very nice display, yours, I assume?

Thanks for posting it.

2nd Dec 2017 12:52 GMTDennis McCoy

Yes Rolph, this is the top shelf of my office bookcase. All of these pseudomorphs are from the American Southwest, except for the copper pseudo from Bolivia and the small radial cluster from Argentina. (I guess they’re American Southwest too, just WAY Southwest!) The left rear example is a “Coyamito agate” replacement from Sonora Mexico.

21st Feb 2018 20:37 GMTLarry Hulstrom

I would appreciate it if anyone still following this discussion could help me identify the specimen shown below. I got it as part of a collection. A friend thought it was quartz after aragonite.

Thanks, Larry

21st Feb 2018 21:45 GMTErik Vercammen Expert

From the picture, I think your frind is right. Pseudo's like this one are found in Argentinia, and in Southern Texas, the Woodward ranch area near Big Bend.

21st Feb 2018 21:45 GMTKevin Conroy Expert

I think that quartz (chalcedony) after aragonite is right. Similar looking specimens were found in Utah.

23rd Feb 2018 13:26 GMTRolf Luetcke Expert


This is one I just took the photograph yesterday. Had to study the small pocket a bit before I figured it all out. First saw the hollow crystal on top of the wulfenite and saw it was cerussite, or had been. It is a cast of quartz that had grown over the cerussite and then the cerussite was etched away. There are some complete cerussites still deep inside the pocket but several had only the quartz cast left. The combination here was so nice with lots going on.

24th Feb 2018 14:02 GMTRolf Luetcke Expert


Photographing mimetite yesterday I came across this hematite pseudomorph after calcite. Actually three colors, the original black below and then bright red and yellow iron replacing the calcite over the original. The mimetite I was looking at can be seen out of focus at the top of the photo. The pseudomorphs were secondary but on close up under the microscope they jumped out at me.

1st Mar 2018 14:32 GMTRolf Luetcke Expert



Here is another one from the same specimen as the previous hematite after calcite. This one poses a bit of a dilemma. The specimen is an iron oxide epimorph after hemimorphite with the hematite after calcite also. The problem is there is no category on the Potosi Mine to post this photo. I myself use limonite but know that is a "loose" category and not an actual mineral. Problem comes in is what to use to replace this name. Interesting replacement but no actual name to place it under. I wonder what others think about this?

1st Mar 2018 16:22 GMTHarold Moritz Expert

On the photo upload form, you can select Other Photo and then select a Type of Photo from the pull down menu. Perhaps "Unidentified Mineral" or "Miscellaneous"?

1st Mar 2018 18:25 GMTRolf Luetcke Expert


I know what it is, iron oxide that most people call limonite but managers didn't like my use of limonite since it is technically not a mineral but that is what it actually is. The only problem I had was not that it was not identified but how to post it to make everybody happy.

1st Mar 2018 18:50 GMTHarold Moritz Expert

Understood, then just select a photo type you're happy with.

2nd Mar 2018 22:06 GMTRolf Luetcke Expert

Solution to the limonite problem seems to be to use goethite and in the explanation on the piece mention the iron hydroxides so this one has been solved, thank you all.

2nd Mar 2018 23:29 GMTJohn Montgomery Expert

Muscovite after Schorl . Personally collected

3rd Mar 2018 01:57 GMTReiner Mielke Expert

Hello John,

You sure it isn't chlorite after schorl?

3rd Mar 2018 02:08 GMTJohn Montgomery Expert

Hi Reiner

Yes, it was ID'd by Michael Bainbridge... in person.

Also, check out a similar specimen of Phil Belley from the same locality

I think Phil saw mine in person as well.


3rd Mar 2018 13:53 GMTRolf Luetcke Expert


This is a jarosite that has been replaced by hematite with small spheres of lustrous hematite overgrowth in a quartz pocket lined with hematite. We collected the specimen on the dumps at the Reef Mine in SE Arizona.

25th Mar 2018 14:08 BSTRolf Luetcke Expert


This is an epimorph after cerussite from the Defiance Mine in Arizona. I know the what it was part but have no idea what mineral is now there? The surface has tiny crystals but they are too small to get a view of to give an idea. The original cerussite is still easy to tell.

25th Mar 2018 14:46 BSTKevin Conroy Expert

Descloizite maybe?

25th Mar 2018 22:24 BSTRolf Luetcke Expert


Thought of that but just couldn't see any actual crystals, too small. Descloizite is out there and has this color.

Thanks, will put it as a possible on the label.

2nd Apr 2018 03:05 BSTAM Mizunaka Expert

Chalcedony replacing calcite.

2nd Apr 2018 19:31 BSTRolf Luetcke Expert


Very nice piece and photo.

Today I was looking at some Bisbee material and one malachite had some interesting things on the broken back side. Limonite had been replacing the acicular malachite. Some of the malachite was still on the specimen but much had been replaced. Cuprite was also on the specimen.


2nd Apr 2018 22:07 BSTReiner Mielke Expert

Hello Rolf

I don't think that is a likely thing to happen. That is most likely primary goethite.

3rd Apr 2018 01:28 BSTRolf Luetcke Expert


I studied the piece and there are places on the specimen where the malachite is still in the acicular form and only the tips have changed and other places the whole crystals have been replaced and some with part of the malachite still visible. I studied the piece a lot before putting this photo on mindat. I have found a lot of replacements in Bisbee I never expected and this one was from the Lavender Pit. The iron oxides did a lot of things in Bisbee.

23rd May 2018 14:14 BSTRolf Luetcke Expert




This is a specimen I had in my mineral room and put into a perky box the other day. As I was studying the piece it opened up a bit of a picture but left some questions. The original mineral was certainly azurite and it shows another mineral in the process of being replaced. The first photo still shows the azurite crystals. The second photo shows most of the azurite having been replaced. The green mineral is one I have found on a few pieces from the Last Chance mine but have no idea just what it is. In the third photo, one lone azurite is completely replaced and is now white. I don't know if it is a different mineral from the green but it was all on one surface, just farther over on the piece. Started off as the azurite and ended up with the white replacement at the other end.

Definitely a pseudomorph but still no clear picture of what the green actually is. Some time down the road I may try and get it analyzed.

23rd May 2018 19:02 BSTWayne Corwin


Could we see a photo of the whole piece?

I've had copper sulphate do the same thing.

23rd May 2018 19:33 BSTRolf Luetcke Expert




Here are a couple of photos of the whole piece, not too big but one can zoom in and see the whole area. To the right are where they seem to turn mostly white.

The crystalline green material we thought was malachite but it has kind of a sugary nature and we had not seen malachite do this.

It is interesting material and we assumed it may be post mine but hard to say since the azurite is so crisp in the specimen with nothing coating them.

Hope this helps with your viewing.

23rd May 2018 20:08 BSTWayne Corwin

Sure be interesting to find out what it is and whats going on.

Keep On Rockin'

23rd May 2018 21:23 BSTKevin Conroy Expert


24th May 2018 00:36 BSTJohn Montgomery Expert

Sorry Reiner I missed your comment.... no, this is correct.... ID'd by both Michael Bainbridge and Phil Belley... sorry for the repeat photo...Almost a complete pseudomorph of muscovite after schorl 11.3cm (personally collected)

25th May 2018 00:27 BSTRolf Luetcke Expert


This one is also from the Last Chance Mine I posted the previous specimen photo of. This one has me stumped. The crystal shape is very much like brochantite crystals I have from here but they are blue. In azuite-malachite, the malachite always replaces the malachite, never the reverse. In this case I have no clue what is going on but I have not heard of azurite after brochantite. It is a tiny spot so no analysis on the horizon, just thought I post this for a nice puzzle.

25th May 2018 00:28 BSTRolf Luetcke Expert

Oops, in the above I meant to say the malachite replaces the azurite and messed up.

25th May 2018 00:42 BSTKevin Conroy Expert


Just to be clear, which Last Chance Mine in Arizona is this from?

25th May 2018 13:41 BSTRolf Luetcke Expert


It is the Last Chance Mine in Courtland.

Used to be lots of great material at this mine but lots of collecting over the years and the mine is pretty well picked over. Only digging can expose some decent material these days. Most of my collecting was done there in the 1970's and 80's.

25th May 2018 14:05 BSTHarold Moritz Expert and other views.

Recently added some close-up photos of the structure of ferberite pseudomorphs after scheelite, Trumbull, Connecticut, USA. Broken surface shows replacing grains have bands of radial structure and the boundary between the two minerals is very sharp. Replacement started in many places leaving multiple remnants of scheelite. This piece is very typical.

13th Jun 2018 23:12 BSTRolf Luetcke Expert


A friend was doing a drilling project at the Queen of Sheba Mine in Maricopa Co. Arizona a while back and brought me a box of samples he picked up at the mine. Great stuff and nice plancheite, hematite, quartz and much more.

I took out the box of specimens from there and was working on labeling ones I had not put labels on when I found a quartz with one blue crystal. I took the photo and when I had it enlarged up on the screen I saw the odd epimorphs after fluorite at the lower parts. I don't know what mineral replaced the fluorite but there are a few odd shapes, including one that resembles an hour glass. Fun little find after at first only seeing the quartz. The light blue here is chrysocolla and plancheite is also on the piece.

15th Jun 2018 04:04 BSTRolf Luetcke Expert


This little piece is on a specimen with plancheite, not visible in this photo but the original crystal here was a pyrite that has been replaced by hematite. In the hollow space inside are brown hematite crystals with a nice reddish glow. The piece is small but quite interesting to me.

15th Jun 2018 04:09 BSTRolf Luetcke Expert



These two photos are from a plancheite specimen but there was a lot going on in the piece. The long, greenish-blue crystals were originally gypsum from the curved parts in the one photo, that have been replaced by chrysocolla. There is also a replaced quartz crystal in one photo but I am not sure whether it was replaced or is just totally included by either the chrysocolla or plancheite. Since it is the only crystal on the piece, not much testing to do without ruining it.

15th Jun 2018 21:58 BSTScott Rider

Pretty cool pseudomorphs Rolf!!! I love that last image, the blue quartz is stunning! I too wonder if it is a true pseudo or if its included/coated. Looking at it, it does almost look like its been converted into the blue mineral... But hard to tell with those tiny guys!

I have been getting into pseudo's lately since I have been looking at my Houselog Creek specimens again! I need to get a better camera to get some of the pseudos that are hollow, but have dendrites inside, giving them a unique look. I'm scouting a new spot there tomorrow, perhaps I'll find some new pseudos and if not, I'll go to where I know there are some! I'll post them Monday.

5th Jul 2018 23:54 BSTChris Rayburn

I've joined Scott Rider on a couple of collecting trips to Houselog Creek here in Colorado ( and finally found a couple last Sunday that can hold a candle to his better pieces. These are chalcedony pseudomorphs and epimorphs after calcite. The first is a cluster of scalenohedrons up to 1 cm; the second is a modified rhomb that's approximately 2 x 3.5 cm, with a sprinkling of smaller rhombs. These occur in red jasper geodes in an altered rhyolite (I believe). They are often quite brittle and can be difficult to extract intact, although the host rock is quite soft.


6th Jul 2018 00:49 BSTHarold Moritz Expert

Some recent pseudos I've posted:

Pumpellyite after analcime:

Quartz epimorph on dissolved anhydrite:

Quartz epimorph on dissolved fluorite with hollow quartz pseudos after fluorite inside:

Actinolite after enstatite:

25th Jul 2018 13:27 BSTRolf Luetcke Expert



Came across these two pseudos of hematite-limonite after calcite yesterday. They are from old, approx. 1887 overburden from the Bisbee mines, close to the Copper Queen Mine that was used near Fairbank Arizona to build a railroad bed. We have collected on this old railroad bed a number of times and it is very interesting to find these old specimens where the old dumps in Bisbee from this time period have long been removed.

18th Oct 2018 13:37 BSTRolf Luetcke Expert




This is a piece I came across yesterday. It is what seems to me a hematite pseudomorph but after what? I first thought it was after cuprite but looking closer at the crystals under the highest power I had doubts. Hard to get good photos of the third tiny cluster but the grouping of crystals in this photo reminded me of descloizite or mottramite. I have found descloizite in the SW Mine before in brown xls but these are red-brown, an obvious replacement. No idea what the original crystals were since they have been completely replaced. So, analysis won't help here. They were a pretty scene on the lustrous background goethite and with the green malachite made for a pretty scene but still a mystery as to what the original crystal were.

27th Oct 2018 21:05 BSTRolf Luetcke Expert


Although this is a discredited species, there is still a lot of replacement going on here. From what I understand the bisbeeite is a replacement after shattuckite, which is probably a replacement after original malachite and it may be altering in places to chrysocolla. Kind of an interesting series.

6th Dec 2018 19:20 GMTRolf Luetcke Expert



These are two pseudomorphs of an unknown mineral after cuprite from the Majuba Hill Mine in Nevada. The first photo has larger, cubic crystals at left and then elongated chalcotrichite which has been replaced. The second photo has a few blue clinoclase also. If anyone knows what mineral replaced the cuprite, would be nice to know.

18th Dec 2018 18:57 GMTDennis McCoy




Here are photos of another pseudomorph/epimorph, this one from Romania. It has similar casts of calcite, with smoky quartz, sphalerite, fluorite and possibly galena.

The casts on this one are larger than the Aggenies example, and much larger than the UK example.

Can anyone help me narrow the location? The label just says “Romania”.

Sorry, this is in reference to my earlier posting “A Tale of Two Epimorphs”.

18th Dec 2018 19:02 GMTDennis McCoy



More pic’s

21st Dec 2018 02:48 GMTAlex Venzke

Analcime with aegirine and calcioancylite PS after remondite from Mont Saint-Hilaire, Quebec, Canada.

31st Jan 2019 01:24 GMTPavel Kartashov Manager

Partial pseudomorphoses of Neptunite after laths of Zektzerite (around central part of the sample) in quartz-microcline pegmatite with black prismes of Aegirine, and big grain of dark-brown primary Neptunite. Dara-i-Pioz, Alai range, Tajikistan.


11th Feb 2019 13:05 GMTRolf Luetcke Expert


This piece I had stored away and came across it yesterday. The first study showed the nice crystals and at first thought the malachite was just a coating but on examining the whole piece, I found some broken crystals and they showed no cuprite left inside so it is a pseudomorph and seems a coating of the nice acicular malachite over the solid replacement underneath. Fun little find on a piece I had for years and had not looked at in a long time.

22nd Feb 2019 16:25 GMTRolf Luetcke Expert


Crystals we collected a few years ago from the Ligier Quarries near Dragoon, Arizona. Took this photo just a day or so ago. The crystals are quite sharp and these here are interpenetrating crystals. Crystals are quite sharp still since they were not far from the original host rock they had formed in.

16th Apr 2019 14:27 BSTRolf Luetcke Expert



These are two new pseudomorphs I received recently from Chris Rayburn, who collected them this year in New Mexico. They are after unknown minerals but I think they could be replacing dioptase, which is quite abundant at the location. Thanks Chris.

17th Apr 2019 23:44 BSTChris Rayburn

My pleasure Rolf. I'll keep finding 'em if you keep identifying 'em!

19th Apr 2019 21:04 BSTRolf Luetcke Expert


This is an odd pseudomorph from the Morenci Mine in Arizona. The specimen has numerous clusters of these elongated crystals of pure chrysocolla after an unknown mineral. In some places the chrysocolla has been partly replaced by chalcedony and some are mixtures of chrysocolla and chalcedony but in this case, the replacement is now chalcedony in tiny, rounded forms. I do not know what the original mineral was that has been replaced here. The whole thing is coated by a dusty layer of limonite.

25th Apr 2019 23:16 BSTRolf Luetcke Expert


A few years back at a dealer room at the Tucson show someone had a flat of coronadite specimens from the Glove mine., I purchased them, not having seen much of these in the past.

The specimen has a lot of super thin wulfenite crystals in all stages of being replaced. Near this one were some broken ones where there was no wulfenite in the crystal left. Not a particularly pretty one but the thinness of the coronadite was interesting.

17th May 2019 20:25 BSTRolf Luetcke Expert


This malachite pseudomorph after azurite is fair size for Bisbee and a gift from Richard Graeme.

17th May 2019 20:44 BSTRolf Luetcke Expert


This one I know two things, the where, SW Mine in Bisbee and that it is a pseudomorph but what the minerals were is unknown. I can only assume that the replacing mineral is an iron oxide and that the original mineral could have been malachite but those are only educated guesses. Lots of these kinds of things that I found in the SW mine when I lived in Bisbee that are unknowns.

This was a cool little piece.

17th May 2019 21:21 BSTDennis McCoy





Aracuai, Jequitinhonha Valley, Minas Gerais, Brazil

2 in x 1-1/2 in

This pseudo was described as being muscovite after tourmaline. I can’t find any comparable specimens represented in Mindat photos. Has anyone seen this material before?

17th May 2019 21:57 BSTBranko Rieck Expert

I really like these pseudos after cuprite:

18th May 2019 13:12 BSTChris Rayburn

Dennis' specimen above reminded me of one that I found several years ago at the Brown Derby #1 Mine in Gunnison County, CO. Lepidolite ps. tourmaline, 0.8 cm x 3 cm. I understand the term lepidolite has been discredited, but...old dog...


18th May 2019 15:42 BSTRolf Luetcke Expert


Wow, that is one wonderful malachite after cuprite!! That is the kind of mineralization I really like and have found similar in SE Arizona. Not in the nice association with the great background. Wonderful piece and photo.


Good to see you posting on the thread as well.

18th May 2019 23:24 BSTRolf Luetcke Expert


This is a replacement of malachite after azurite from a famous Australian mine.

18th May 2019 23:27 BSTRolf Luetcke Expert


This one is a bit odd, the original mineral is acicular malachite and it has been replaced by chrysocolla but it is more green than the typical blue.

19th May 2019 15:25 BSTBranko Rieck Expert

Thank you, Rolf!

Here is another one from the same locality:

19th May 2019 16:46 BSTRolf Luetcke Expert


Another beauty!! Funny, the Hilarion area seems to have a lot of similarity with minerals as some of the mines here in SE Arizona. I collected a lot at a small location called Last Chance Mine in Courtland Arizona and found a lot of similar specimens. Maybe not as nice as yours but not bad for self collecting things. Bisbee also has a similar association at places.

I may have posted this one earlier but thought I put it in here since the background pseudos are similar in color to the iron oxides on yours from Hilarion.

19th May 2019 20:12 BSTRolf Luetcke Expert



Here are a couple I took photos of today.

First one is from a local mine near Dragoon Arizona, an original, curved malachite, that was replaced by chrysocolla.

Second one is a limonite replacement of original smithsonite from the Omega Mine in Arizona.

20th May 2019 23:14 BSTRolf Luetcke Expert



From the Ojuela Mine in Sonora Mexico I came across the malachite pseudomorphs after cerussite. There is a bit of cerussite in a few of the crystals but most are completely replaced. There is a second generation of lighter malachite on the pieces also. Wulfenite is present in small crystals and there is some iron oxide coating, presumably hematite on the pieces also.

20th May 2019 23:17 BSTRolf Luetcke Expert



A couple more malachite pseudomorphs after azurite. First one is from the Tiger Mine at Mammoth Arizona, second one from Milpillas Sonora Mexico.

21st May 2019 06:32 BSTBranko Rieck Expert


I really like this thread. Here another contribution from me:

Yellow-green nickellotharmeyerite (XRD- and EDS-analysed) pseudomorphing a millerite spray within a carbonate matrix.

23rd May 2019 14:04 BSTRolf Luetcke Expert


This one I wanted to post since it was sold as a "pseudomorph" from the Mission Mine in Arizona. It is only the two tiny crystals on a mount in a micro box. Since there is not enough to break one to see if it is an actual replacement or only covered by malachite I posted it as a cuprite with malachite coating. Seems that one corner is slightly damaged and seems the cuprite is showing from below. Hard to be sure in this case since I don't want to ruin the specimen. Thought it may fit in the thread as a "maybe" specimen.

23rd May 2019 14:34 BSTKevin Conroy Expert

I might be stretching the boundaries of this thread, but here's an epimorph from the Sweetwater Mine in the Viburnum Trend, Missouri, USA. This epimorph formed when marcasite grew over a sharp anhydrite crystal, then the anhydrite naturally dissolved away. These oddities are fairly rare in the Viburnum Trend. 5.6 cm x 2.3 cm x 0.5 cm

23rd May 2019 17:02 BSTRolf Luetcke Expert


I intended the thread to be "loose" in definition so those cool pieces are very welcome.

Thanks for posting.

23rd May 2019 19:05 BSTKevin Conroy Expert

One of my favorites, this galena after pyromorphite is from Wheal Hope, Cornwall, England. 5.4 cm x 3.7 cm x 3 cm

23rd May 2019 21:03 BSTRolf Luetcke Expert


Great piece!!

24th May 2019 01:05 BSTAM Mizunaka Expert

Quartz mostly replacing elbaite. A thin veneer of elbaite remains on the front of the specimen.

24th May 2019 11:10 BSTPaul De Bondt Manager

AM, not sure this is a pseudo. More quartz growing on elbaite.

If a pseudo, the quartz would have conserved the shape of the elbaite and this is not the case here.

24th May 2019 11:21 BSTWayne Corwin

I think Paul is correct, the quartz is an overgroth, not pseudo.

24th May 2019 19:18 BSTAM Mizunaka Expert

The core of the elbaite has been replaced by quartz and has continued to overgrow the crystal.

24th May 2019 19:38 BSTWayne Corwin


Can we please see photos from the top, back and bottom too?

24th May 2019 20:09 BSTAM Mizunaka Expert

Description from the dealer:

"An amazing example of this rare Pseudomorph where Quartz is replacing and overgrowing a tourmaline. A mint green Elbaite crystal is almost completely replaced with just an exterior skin remaining. The core is now pure quartz and the original termination is capped with terminated Quartz prisms. This was found several decades ago and stands apart as an especially esthetic example. The front view of this is the obvious display side but the back and underside are especially interesting as they show the transition well."

Photos of the back and core of the specimen from the original dealer listing.


25th May 2019 03:13 BSTKevin Conroy Expert

Yellow cadmium smithsonite after dolomite is the main attraction of this specimen from the Monte Cristo Mine, Rush, Arkansas, USA. A secondary deposit of cadmium smithsonite dots the previous deposit. Also present are sphalerite crystals which have undergone some dissolution. 33 cm x 17.5 cm x 12.5 cm

26th May 2019 21:14 BSTRolf Luetcke Expert



Light blue plancheite pseudomorphs after quartz from DR Congo.

26th May 2019 22:45 BSTKelly Nash Expert

This is a 5 cm. powellite pseudomorph after molybdenite (with a dusting of malachite). On the other side (right), you can see some unaltered molybdenite in the core. Collected at the Jardinera No. 1 mine, Atacama, Chile, by Terry Szenics in 1994.

27th May 2019 16:13 BSTKevin Conroy Expert

Nice specimen Kelly!

Here's a floater twinned orthoclase crystal has pseudomorphed into topaz, from Saubachriss, Germany. Dimensions: 3.3 cm x 2.4 cm x 1.4 cm

27th May 2019 17:43 BSTDon Windeler


Nice topaz pseudo -- I've always liked those and manage to keep accumulating them . (Have a photo of one currently in the approval queue!)

This is probably the biggest pseudomorph in my collection, with cream-colored disks of calcite that replaced some kind of acicular mineral. From the Renison Bell mine in Tasmania, 16 x 10.5 x 10 cm. One of these days I need to reshoot it so the lighting's not so muddy.

27th May 2019 20:19 BSTRolf Luetcke Expert

I thank all for posting to this thread, love seeing all the varieties of pseudomorphs people have and a few I had not seen before.

I sure agree, Kelly's is a great piece.

Kevin, had not seen those so something new for me.

27th May 2019 22:29 BSTDon Windeler

I meant to mention how much I like Kelly's powellite pseudo. I have a reference example of this replacement, but it's small and ugly -- the one Kelly showed is fantastic.

Here's something a little different. I did my MS thesis in the skarns of the Yerington district, Lyon Co., Nevada. One of the foundational publications on the area is the 1918 USGS Professional Paper 114 by Adolf Knopf. This is Plate IIa from that report and shows a Halobia fossil in a limestone protolith replaced by grossular-andradite garnet, found somewhere west of the McConnell Mine. I've been tempted to post this is in the Yerington district photos but don't actually have any information on size of the specimen --MinDat gets grumpy if that's not included.

I've often wondered where this specimen currently resides; as a fan of specimens from the Yerington district and a pseudomorph guy, I've long lusted after it!



28th May 2019 06:22 BSTJobe Giles

I have often questioned if these are pseudomorphs or epimorphs or... just some weird twinning. The formations taper towards the base forming an almost inverted pyramid. Either way, fascinating Hoppered Albites. El Dorado county, CA.



3rd Jun 2019 15:07 BSTRolf Luetcke Expert



Black martite, a hematite pseudomorph after magnetite from Utah.

5th Jun 2019 15:17 BSTRolf Luetcke Expert


I had posted one from a different location before but this one I just took the better photos of yesterday and it is a massicot after what I believe is cerussite, from Arizona.

5th Jun 2019 17:21 BSTTony Nikischer Manager

First reported occurrence of oxyplumboromeite as a pseudomorph after bournonite, from the Yaogangxian Mine in Yunnan Province, China in early 2019. It is the most complete, well-formed example of the find, although not the largest. The specimen stands 4 cm tall and sits on a small matrix of drusy quartz crystals. EDS and PXRD confirmed, published in Mineral News, Vol. 35 No. 6.

5th Jun 2019 20:13 BSTRolf Luetcke Expert


Cool piece! Thanks for adding it to the thread.

8th Jun 2019 00:05 BSTDon Windeler

Thought I’d have a little fun with this one and put together a group therapy session of “I Used To Be a Feldspar” from my pseudomorph collection. FOV is about 30 cm in width, individual specimen dimensions in linked photos.


spessartine after orthoclase, Lac Duhamel, Mont Tremblant, Quebec

quartz and schorl ps. microcline, Erongo Mts., Namibia

lazurite ps. orthoclase, Cerro de Potosi, Bolivia

kaolinite ps. orthoclase, North Goonbarrow China Clay Pit, Cornwall, England


lepidolite ps. orthoclase, Muiane pegmatite, Zambezi Province, Mozambique

cassiterite ps. orthoclase, Wheal Coates, Cornwall, England

epidote ps. plagioclase, Ann-Mason deposit, Yerington District, Lyon Co., Nevada

topaz ps. orthoclase, Saubach, Saxony, Germany (possibly Schneckenstein)

gonnardite ps. hauyne, Sar-e-Sang, Badakshhan, Pakistan

[Note that this interloper was originally purchased as hauyne ps. plagioclase, but was corrected in the approval process based on the 2014 MinRec article.]



8th Jun 2019 15:12 BSTRolf Luetcke Expert


Great photo and idea, thanks so much. Kind of fits into this thread and the Just for Fun one!

Nice group of pseudos too. Good idea about putting them in as a group. Might even give others an idea for what can be done, maybe for their own therapy!!

8th Jun 2019 21:25 BSTRolf Luetcke Expert




This one is a bit of a mystery. I got it for all of $2.50 from a Tucson dealer years ago. It was labeled as "Melaconite" which is the old term for tenorite. Tenorite has been a big problem over the years since almost all of the tenorite a friend tested at a lab turned out NOT to be tenorite. Tenorite is almost always closely associated with cuprite as it is a nearly direct alteration from this mineral. In this case the chemistry is just wrong for tenorite and I don't know what the black coating over the specimen is but probably nothing similar to tenorite.

The other mystery is what the green inner part is as a replacement. I assume it is a green chrysocolla but it is only a best guess. In the inner portions of the original smithsonite, and I am pretty sure it had been smithsonite, there are a few tiny crystals that could be smithsonite or may be calcite. It is a nice pseudomorph but exactly what has gone on is a bit of a mystery.

8th Jun 2019 22:00 BSTKevin Conroy Expert

Rolf, the form of the suspected chrysocolla looks like some that I've seem from the Miami area. Out of curiousity, what mineral(s) were the tested "tenorite" specimens confirmed to be? Until I read your description I never gave the dark stuff on these specimens a second thought. Looking at this closely, hisingerite MIGHT be a possibility, but that's definitely a wild guess on my part!

8th Jun 2019 22:39 BSTRolf Luetcke Expert


Sent you a message about this.

To briefly say here, many turned out to be black chrysocolla with coloring agents of iron or manganese.

18th Jun 2019 21:56 BSTBranko Rieck Expert

Something I have never seen before appeared in this spring's crop: a pseudo of parnauite (PXRD) after an unknown precursor. Hope you like it!

18th Jun 2019 22:50 BSTRichard Gunter Expert

Hi Rolf:

The powdery inner part of the smithsonite pseudomorph may be sauconite. It has the correct chemistry (Zn-rich clay). I have a very similar sample from the 79 Mine and the interior of the pseudomorphs are clay-like. Does your sample have hemimorphite on it as well?

18th Jun 2019 23:05 BSTRolf Luetcke Expert


Cool crop of parnauite you have there! Love all the alterations at Lavrion! We have some of the same here in SE Arizona, lots of alteration, both in the ore body and post mine.

W. Richard,

Yes, there is a bit of hemimrophite on the side of the specimen. Thanks for the heads up on the sauconite, will look into that. Appreciate the hint.

Thanks all.

19th Jun 2019 18:41 BSTDennis McCoy

Getting ready to change out this display in my office; thought I’d share it first. Some of you may not appreciate my calling these pseudomorphs, but they fit the original use of the word.

Assorted corals, clams, nautilus, sponges and etc.

The shelf is 24” wide, for size reference.

19th Jun 2019 20:46 BSTDon Windeler

Nice, Dennis -- I sometimes refer to pseudomorphs as "mineral fossils" for talks or displays aimed at the general public.

And sometimes fossils can be really cool mineral specimens in their own right ... as a fan of pseudomorphs, I would maim to get one of these:

A snail replaced by emerald? How cool is that?


19th Jun 2019 21:27 BSTRolf Luetcke Expert


My whole intention on starting the thread was to let people post things with a wide leeway, I was not trying to be too restrictive, but for folks to show their favorites. Love that display, very nice to look at and thanks for posting it.


Yes, super cool, have seen those as pyrite replacements but never beryl, very cool.

20th Jun 2019 15:01 BSTEd Clopton Expert

O.k., I finally checked out this thread. Lots of interesting specimens and discussion.

Here are some of my favorites. This pair of thumbnails (azurite and malachite after azurite, Ray, Arizona), purchased together at a rock shop in Colorado, got me started on a quest for "before and after" pairs:

This is my closest dead-ringer before-and-after set, scapolite (presumably marialite), Morogoro, Tanzania, and feldspar after scapolite, Kartoum, Ontario, Canada:


I won't be able to afford a comparable "before" specimen to accompany this specimen of erythrite and kaolinite (and probably other stuff as well) after cobaltite, 5 cm, larger crystal 12 mm, Espanola, Ontario, Canada:

And here are links to some favorite pseudomorphs from my collection already on Mindat:

Turquoise after beryl, Apache Canyon, California (I purchased the specimen from John Betts in 2003 and discovered just today that his photo of it has been online since 2002!)

Quartz epimorph after a fan of stout anhydrite bars, Prospect Park, New Jersey

Dolomite after calcite, Remigiusberg quarry, Rammelsbach, Rheinland-Pfalz, Germany

Quartz after calcite, Těškov, Rokycany District, Plzeň Region, Czech Republic

Pyrite after calcite, San Antonio Mine, Santa Eulalia District, Chihuahua, Mexico

Strontianite epimorph after calcite, Convict Hill Quarry, Oak Hill, Travis Co., Texas, USA

Gypsum after huge halite crystal, Glass Mountains, Oklahoma

And of course there's more . . .

20th Jun 2019 20:36 BSTRolf Luetcke Expert


Nice idea with matching original and pseudos in a collection, that could be quite hard to match up but in a couple of cases, you did quite well.

In the one pyrite after calcite from the San Antonio Mine in Mexico, I have some from Mexico with no mine and after seeing your piece, sure looks like it could be from this mine. Will have to do some investigating.

Thanks for posting those.

Here are a couple I worked on getting better photos of today.

No original mineral left in broken areas but its green color suggest malachite as the original mineral.

This one had original baryte crystals in some broken spots and others there was no baryte left.

22nd Jun 2019 00:22 BSTRolf Luetcke Expert



These two are minium pseudomorphs. First one is easy, after cerussite. The German one has me a bit wondering what it replaced. Kind of has the shape of wulfenite but not quite sure and no reference pieces on mindat to show other pseudos from there.

4th Jul 2019 21:13 BSTRolf Luetcke Expert


Don't recall if these were posted before on the thread but I took this photo just a couple of days ago and figure I put it in as the muscovite after cordierite from Japan. Those used to be fairly common but have not seen them in a bit.

4th Jul 2019 22:56 BSTAlfredo Petrov Manager

Rolf, you could also label them as muscovite after indialite, because the center of the flower was indialite, and just the petals were cordierite.

5th Jul 2019 15:22 BSTRolf Luetcke Expert

Thanks Alfredo, I had read that but hadn't differentiated the replacements.

6th Jul 2019 05:46 BSTTony Charlton

Rutile (variety sagenite) after brookite, in quartz.


6th Jul 2019 21:24 BSTAlfredo Petrov Manager

For anyone interested in beautiful pseudomorphs, and the chemistry of their formation, I recommend a recent article by two professors from the University of Zaragoza, Spain...

Jesus Fraile and Miguel Calvo (2019) Pseudomorphs - When the mineral is not what it was. Mineral Up, 2019 No. 1, pp 8–30.

...with extensive bibliography.

6th Jul 2019 23:06 BSTDon Windeler


Thanks for flagging this article -- definitely want to get a copy for my reference library.

Pardon my ignorance, but how does one get to Mineral Up magazine? I did some searches and was directly to some links on Facebook -- which I don't use -- and to a link on Jordi Fabre's site that seems to redirect to a cosmetics site in Japanese. Would be willing to buy a copy of the issue, but my search fu is weak today.


7th Jul 2019 00:04 BSTAlfredo Petrov Manager

Don, I think Gloria at Lithographie is the official distributor in the USA, but this issue was printed a few days ago, just in time for the Sainte Marie show, so not sure how long it takes to get to the U.S. (I got a copy at the Luban show in Poland today.)

If I can make it to the SF show this year, I will bring you a copy. (What dates is the SF show this year, by the way? info on the club website last time I looked.)

7th Jul 2019 05:17 BSTDaniel J. Evanich Expert


The SF Show is August 3-4 this year, 2019. As usual, I'm putting a display case together for BAM. Bring me a copy, too!

7th Jul 2019 05:23 BSTDon Windeler

Thanks, Alfredo -- I actually saw Gloria at a small event in Marin last Saturday, but too bad I didn't have an excuse to talk about pseudomorphs! I'll ping her, no rush.

The SFGMS show is August 3-4, listed on their club site as well a a dedicated show site ( ). Unfortunately I'll miss it this year due to other plans. Bummed about that, as it's always one of my favorite shows in the area -- really enjoy the dealers and displays.



7th Jul 2019 16:21 BSTEd Clopton Expert

For some reason Don's link to the San Francisco Show web page doesn't work, but this one worked for me:

The article by Fraile and Calvo sounds interesting. I'll try to figure out a way to acquire it some day.

7th Jul 2019 17:17 BSTDon Windeler


Thanks for pointing that out -- I've fixed it. The system doesn't like it if the close of the parentheses is right next to the text because it includes it in the URL. Added a space afterwards.

And to stick with the thread topic, here's a fun one to go with the emerald snail I linked above -- unlike that wonderful piece, this rhodochrosite snail is actually part of my collection.



21st Jul 2019 01:40 BSTRolf Luetcke Expert


This is a specimen I collected at Getchell in the 1970's. The pararealgar has replaced some of the smaller crystals completely and the larger ones only partly.

31st Jul 2019 00:13 BSTRolf Luetcke Expert


A friend brought over some material at a project he was working on at the Mexican Hat in SE Arizona. There was a pocket of nice, green malachite and not far away, another pocket of blue chrysocolla having replaced the malachite.

8th Aug 2019 21:43 BSTRolf Luetcke Expert

A polydymite replacing original millerite crystals.

8th Aug 2019 21:45 BSTRolf Luetcke Expert

Second photo of the polydymite replacing original millerite.

26th Aug 2019 22:42 BSTRolf Luetcke Expert

I have posted single crystals of these pseudomorphs from St. David, Arizona but thought I put together a group of the more interesting forms.
The crystals are shown on the St. David page but not in a group.  I have only found these crystals in one small area of one small canyon.
The two broken ones in the second row and the one very long one in the 4th row, show the calcite crystals that grow toward the inside of the crystals.

27th Aug 2019 06:13 BSTGareth Evans

Payún volcano, Altiplano de Payún Matru, Malargüe Department, Mendoza Province, ArgentinaDimensions: 100 mm x 70 mm x 60 mmThe specimen displays parallel and skeletal growths of octahedral hematite pseudomorphs after Magnetite. It is covered by a second generation of small laminar crystals of Hematite. This specimen was photographed for the ‘what’s new at Munich 2008’ section of the magazine ‘Mineralien Welt’ and appears on page 16 of number 1/2009

27th Aug 2019 13:09 BSTTim Saunderson

These are solid clay all the way through, not just a coating.
FOV 4.1mm

28th Aug 2019 15:15 BSTRolf Luetcke Expert

Cool specimen, thanks for posting!
Those are very cool and just the kinds of things I love coming across, also thanks for posting.

6th Sep 2019 20:30 BSTRolf Luetcke Expert

Took a better close up of the sharp crystal surfaces of the malachite that replaced former Gypsum crystals.  Gift from Richard Graeme, 25x25mm specimen.

6th Sep 2019 22:50 BSTJeff Weissman Expert

Rolf, very nice image of a really cool pseudo!

9th Sep 2019 22:18 BSTRolf Luetcke Expert

Here is a pseudomorph from Bisbee of malachite after cuprite in two generations.   Field of view is 6mm and the matrix is iron oxides.

18th Sep 2019 22:35 BSTRolf Luetcke Expert

This is a brown limonite pseudomorph after dolomite and on the inside they are bright yellow, on quartz, 6mm field of view.

23rd Sep 2019 23:56 BSTRolf Luetcke Expert

This malachite after azurite is a bit translucent and the crystals are quite sharp.  It was collected by Jack Hanley, when he was working at the mine.  field of view is 5mm.

24th Sep 2019 02:45 BSTGareth Evans

A lovely Copper after Cuprite consisting of four stacked octahedrons of Copper from the Poteryaevskoe Mine, Rubtsovskoe Cu-Zn-Pb deposit, Rudnyi Altai, Altaiskii Krai, Western-Siberian Region, Russia. The formation of individual copper crystals can be easily seen in the enlarged photo. Specimen is about 90 mm x 40 mm x 35 mm.

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