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Pseudomorphs & Replacements D to I

Posted by Rock Currier  
avatar Re: Pseudomorphs D to I
January 14, 2011 08:51PM
Rock

Don't forget about illite after halite - see [www.mindat.org] and also [www.mindat.org]

Is ice after water really a pseudomorph - if so, I have a *small* supply in my backyard I'd love to sell you. (:P)
Re: Pseudomorphs D to I
January 14, 2011 09:04PM
ca    
Re: Dyscrasite after silver - might this just be dyscrasite or silver after dyscrasite?
avatar Re: Pseudomorphs D to I
January 15, 2011 05:39AM
de    
The ice crystals are not pseudomorphs - otherwise you would have to consider any mineral as a pseudomorph after its melt.
avatar Re: Pseudomorphs D to I
January 15, 2011 12:29PM
Thank you all for your comments and corrections. So far the pseudomorphs articles are not really articles at all, but rather a growing number of pictures of pseudomorphs arranged alphabetically by what they are now. Once all the images are embedded, we can start adding text with information about the various pseudos under their pictures. If you are a manager or a moderator here on the best minerals forums, feel free to start adding comments and writing the text.

Ed, if you specialize in pseudos, why don't you give some consideration to writing up some descriptive comments about the various pseudos that you know about. I can assure you they will be welcome.

Peter, Yes you are right about the Ice, but I feel inclined to leave the pictures in the article with suitable explanation that most consider these not to be real pseudomorphs, but I want to leave them in there to start people thinking about how minerals can change, and they perhaps more commonly do than not. Mercury is a liquid right? Why should we not claim water as a mineral. This is part of my devils advocate position to try and get the IMA and other mineralogists to expand their definition of what minerals are and to reclaim territory lost to other sciences so that we can start the pendulum swinging back the other way and to bring mineralogy more into the mainstream of society and the sciences.

Somewhere I have a picture of Atacamite after mouse that I am going to put in the article. I would love to have a picture of the Copper after ancient Peruvian mine that is in the American Museum of Natural History. I would add that to the article in a heart beat. Perhaps I will badger George Harlow to see if I can get one to upload to our galleries.

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs D to I
January 16, 2011 09:05PM
Rock,

Per comments in "A to C", I'm posting a set of specimens that hit localities and/or replacements not well represented in the articles at present, rather than saying these are all The Best. Thank you for your efforts!


Dolomite after calcite
Santa Eulalia District, Mun. de Aquiles Serdán, Chihuahua, Mexico

Dolomite after calcite
Gánt, Vértes Mts., Fejér Co., Hungary

Epidote after quartz
Pinaleño Mts, Aravaipa District, Graham Co., Arizona

Goethite after gypsum
Santa Eulalia District, Mun. de Aquiles Serdán, Chihuahua, Mexico

Goethite after pyrite
Copper Mountain, Prince of Wales Island, Alaska, USA
Goethite after pyrite probably should get maxed out in the article at some point – lots of places to be found.

Hematite after epidote
Bessemer Ridge, Green Mountain, North Bend, King Co., Washington, USA
Pseudo / loc is already represented, but this is a pretty good example.

Illite after halite
Auburn, Nemaha Co., Nebraska, USA
This loc / pseudo mentioned by Jeff earlier in the thread. This piece is one of my favorite pseudomorphs – really like how it has retaining the hoppering on the halite cubes even though they’re flattened out, almost like bas-relief
Re: Pseudomorphs D to I
January 16, 2011 11:25PM
Hi Rock!
I have added a picture pf plancheite after dioptase from Tantara, it is the sister of the speciment dioptase after calcite on the right, also in my collection. These are old speciments cheriched by Belgian collectors!
All the best
Valère
avatar Re: Pseudomorphs D to I
January 16, 2011 11:30PM
Valere, Could you give me the image number on that specimen?

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs D to I
January 20, 2011 08:40AM
Don,
OK, Its devil's advocate time again.

Dolomite after calcite, Santa Eulalia, Mexico. Good specimen. It could be a little better in focus. What makes you think it is dolomite after calcite as opposed to one of the other rhombohedral carbonates?

Dolomite after calcite, Gánt, Vértes Mts., Fejér Co., Hungary. Looks a bit overexposed. Also are you sure its dolomite?

Epidote after quartz Pinaleño Mts, Aravaipa District, Graham Co., Arizona. It could be epidote, but I don't see any hexagonal crystal shape here. Is it the photo that doesn't show the hexagonal shape of quartz?

Goethite after gypsum Santa Eulalia District, Mun. de Aquiles Serdán, Chihuahua, Mexico. Is there some reason you call it Goethite after Gypsum and not Limonite after Gypsum?

Goethite after pyrite, Copper Mountain, Prince of Wales Island, Alaska, USA Good picture but out of focus. At some point we will need to cut back on the Goethite/Limonite pseudos after pyrite etc. I knocked back a lot of them already, but will probably need to cull them more as the list grows.

Hematite after epidote Bessemer Ridge, Green Mountain, North Bend, King Co., Washington, USA. Yes worthy of inclusion, but out of focus.

Illite after Halite, Auburn, Nemaha Co., Nebraska, USA. Yes, this one is better than what we have and is worthy of inclusion, but why do you call it illite rather than mud or clay. Nothing wrong with the name illite, but I wonder if you have a reason other that that was on the label when I bought it.

Keep on trucking!

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs D to I
January 22, 2011 08:53AM
Rock -- thanks for looking through the pieces. Comments below.

> Dolomite after calcite, Santa Eulalia, Mexico.
> Good specimen. It could be a little better in
> focus. What makes you think it is dolomite after
> calcite as opposed to one of the other
> rhombohedral carbonates?

Trusting the label, mostly. I'll try to see if there are any tests I can do that won't mess it up -- maybe a little acid out of sight.

> Dolomite after calcite, Gánt, Vértes Mts.,
> Fejér Co., Hungary. Looks a bit overexposed. Also
> are you sure its dolomite?

Ditto on this one, just going by the label. The sample is pretty light colored and doesn't show a lot of relief, but maybe I can fiddle with the pic a little or shoot it again.

> Epidote after quartz Pinaleño Mts, Aravaipa
> District, Graham Co., Arizona. It could be
> epidote, but I don't see any hexagonal crystal
> shape here. Is it the photo that doesn't show the
> hexagonal shape of quartz?

Definitely the photo -- if you have this sample in hand, there's no doubt it is/was quartz. I'll try to add another angle that shows it off better.

The main question I've asked myself about this piece is whether the epidote is a replacement or inclusions. I think I've bought into replacement on the basis of the irregular, scalloped interface at the boundary between the epidote and the islands of remnant quartz, but I think you'd need a thin section to really get a look.

> Goethite after gypsum Santa Eulalia District, Mun.
> de Aquiles Serdán, Chihuahua, Mexico. Is there
> some reason you call it Goethite after Gypsum and
> not Limonite after Gypsum?

Once again the label and "common usage" I've seen on other examples. I'd have no beef going with limonite instead, unless you can suggest a test to distinguish the two.

> Goethite after pyrite, Copper Mountain, Prince of
> Wales Island, Alaska, USA Good picture but out of
> focus. At some point we will need to cut back on
> the Goethite/Limonite pseudos after pyrite etc. I
> knocked back a lot of them already, but will
> probably need to cull them more as the list grows.

I'll shoot it again. I agree with you that this is a common enough pseudomorph that the criteria should eventually shift to truly the best examples. This one isn't up to Pelican Point, but I've never seen it from this area and was pretty surprised at the size and sharpness.

> Hematite after epidote Bessemer Ridge, Green
> Mountain, North Bend, King Co., Washington, USA.
> Yes worthy of inclusion, but out of focus.

I'm looking forward to improving my photography. Another reshoot.

> Illite after Halite, Auburn, Nemaha Co., Nebraska,
> USA. Yes, this one is better than what we have and
> is worthy of inclusion, but why do you call it
> illite rather than mud or clay. Nothing wrong with
> the name illite, but I wonder if you have a reason
> other that that was on the label when I bought
> it.

Once again, just the label. All three of these pieces on MinDat are labeled as illite (baaaa...), all are labeled as from Scott Williams, so I suspect someone decided to call the clay there illite. I tried to sniff around for information on the locality; there are numerous references to illite in the Nemaha region as a common weathering product and a specific geologic unit, but that's all I have to go on.

> Keep on trucking!

Thanks -- all good fun.

I'm sort of breaking my own rule of not mis-posting between the pseudo lists, but while looking for examples of epidote after garnet at the Garnet Hill loc in Calaveras County, I was reminded of the impressive quartz after garnet samples found there. I linked to the one good example posted -- wish I had one of those!
avatar Re: Pseudomorphs D to I
January 28, 2011 01:47AM
de    
"Peter, Yes you are right about the Ice, but I feel inclined to leave the pictures in the article with suitable explanation that most consider these not to be real pseudomorphs, but I want to leave them in there to start people thinking about how minerals can change, and they perhaps more commonly do than not. Mercury is a liquid right? Why should we not claim water as a mineral. This is part of my devils advocate position to try and get the IMA and other mineralogists to expand their definition of what minerals are and to reclaim territory lost to other sciences so that we can start the pendulum swinging back the other way and to bring mineralogy more into the mainstream of society and the sciences."


Ice and water are related by a PHASE TRANSITION, which has nothing to do with pseudomorph formation. It is obvious that the ice crystals do not exhibit the shape of the body of water they formed from. This has nothing to do with the question if water is a mineral or not.
Re: Pseudomorphs & Replacements D to I
November 02, 2011 09:14PM
I see a discussion of the Nebraska illites after halites above. I have one of the three pictures and that one has a label from Scott Williams, who I would bet collected all the specimens extant. He was either working on his Ph.D. on SE Nebraska mineralogy at the time or was a professor at Peru State College in Nebraska when he collected these (his bio is on the Min. Rec. website). At the time, he probably had easy access to an XRD unit for ID of the illite, and I am pretty confident he had the right clay mineral. Scott was an excellent mineralogist, and probably the most successful field collector in a very difficult mineral-colllecting state.



Edited 2 time(s). Last edit at 11/02/2011 09:27PM by Kelly Nash.
avatar Re: Pseudomorphs & Replacements D to I
November 04, 2011 07:30AM
Kelly,
I suspect you are right. At one time Scot Williams was a partner with Dave new in Southwest minerals (I think that was the name of their company) which got and sold a lot of good mineral specimens while the partnership lasted. I only met him a couple of times.

Rock Currier
Crystals not pistols.
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