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Pseudomorphs & Replacements A & B

Posted by Rock Currier  
avatar Re: Pseudomorphs A to C
January 06, 2011 02:55PM
    
The pictures shown are "skulls" (a better one is [www.mindat.org] ) which are copper filling/replacement of the interpebble spaces (some rock minerals in the matrix might be replaced).

There are many examples where the cobbles in the conglomerate have been replaced (no photos of this has been uploaded to mindat)

[www.minsocam.org]
avatar Re: Pseudomorphs A to C
January 06, 2011 10:40PM
Dave, yes the one you suggest is better and Ill put it in also. Yes, when I got around to putting in text, I would talk about copper "skuls". The ones we have in the gallery are OK, but they are rather small. Perhaps some day we will get images of some really good big ones. I don't think these are linings of
amygdaloidal cavities, but I think some more or less round rock dissolved and copper came in and partially filled in the space or the copper came in and selectively reacted with the rock and filled in part of the space that the rock used to occupy. What do you think?

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
January 09, 2011 12:15AM
Thanks for the info and link Dave.

That kind of makes sense but it would appear that the ones in Mindat are essentially infills around the pebbles rather than replacement... ok some small parts of the specimens may have been replaced in which case we need tp provide more info and include pics of full replacements.

Cheers
avatar Re: Pseudomorphs A to C
January 16, 2011 09:00PM
Rock:

I’ve been rummaging through my pseudomorph collection in search of samples that might be relevant to this project. I don’t have delusions of grandeur about these, just have tried to pull out specimens that hit localities and/or replacements not well represented in the articles at present. In the “Best of …” spectrum, it seems to me the pseudomorph articles have to cast a pretty wide net; there are so many combinations of X after Y at locality Z that it’s impressive it only covers five articles.

I’ll post similar responses in the other threads. Thank you for your efforts!

Note: in the main article there is a misspelling of “Chalcocie after wood” from Clay Co. TX

Calcite after aragonite
Larimer Co, Colorado

Chlorite after magnetite
Ziller valley, North Tyrol, Tyrol, Austria

Copper after cuprite
Wolf Mine, Herdorf, Siegerland, Rhineland-Palatinate, Germany

Copper after cuprite
Tsumeb, Namibia

Copper “skull” after conglomerate
Osceola Mine No. 1, Houghton Co., Michigan
I like the example David highlighted above as well; I think the example I’ve posted is interesting for also replacing / filling a fracture down the middle. I’m not quite sure how to ID a skull in which the copper completely replaced the underlying rock, though.

Cheers!
Re: Pseudomorphs A to C
January 16, 2011 11:38PM
cerussite after anglesite, miniature, Broken Hill, Australia
VB collection
Attachments:
open | download - 1minéraux pour FB 021.jpg (602.5 KB)
avatar Re: Pseudomorphs A to C
January 19, 2011 09:40PM
Valere,
Thanks for the image of the cerussite after anglesite. However we generally prefer shots where the entire specimen is shown and not just part of a specimen. In addition the only images we use in the Best Minerals articles are those that have been uploaded to the mindat database. This is because of copyright considerations.

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
January 19, 2011 10:07PM
Don,

Calcite after Aragonite - Good enough, added to the article

Chlorite after Magnetite - Good enough, added to the article

Copper after Cuprite, Germany - Not good enough specimen to make the cut. There must be better ones around somewhere.

Copper after Cuprite, Tsumeb - Good enough, added to the article

Copper skull, Michigan, the photo is a bit out of focus, but otherwise good enough to make the cut.

Keep on trucking. Can you add informative comments about the above specimens that are now in the article or the localities they come from?

Yes, so far we have managed to squeeze the pseudomorphs into five articles, but when we start adding descriptive text to them I am sure we will exceed the 60K character limitation of these fields and we will have to break them down into more articles.

Rock Currier
Crystals not pistols.



Edited 1 time(s). Last edit at 01/19/2011 10:32PM by Rock Currier.
avatar Re: Pseudomorphs A to C
January 20, 2011 01:28AM
    
Wolframite pseudomorph after scheelite. Collected 1979. Old Mine Park, Trumbull, CT, USA.
Attachments:
open | download - Wolframite ps. after Scheelite - Trumbull CT 1979.jpg (242 KB)
avatar Re: Pseudomorphs A to C
January 20, 2011 01:44AM
Thanks, Rock. I'll reshoot the copper skull to get it in better focus. Tricky with my camera, as I don't think it has much flexibility on the f-stop. (Either that or I just haven't figured it out. Serves me right for losing the manual.)

I've never seen another copper after cuprite from the Herdorf myself, but that doesn't mean much. I like it as a representation from a classic locality best known for something else.

On that same replacement, though, I just realized there's no representation of the coppers after cuprite from the Itauz Mine in either your list or (surprisingly) the MinDat database. There was a nice find of them several years ago. I have a pretty good one, but need to figure out where I put it!

I'll look over things and see if I know enough to contribute some commentary on any of these samples or localities. Thanks again!
Re: Pseudomorphs A to C
January 26, 2011 08:14PM
I just saw this foto today:
Locality: Rampgill Mine, Nenthead, Alston Moor District, North Pennines, North and Western Region (Cumberland), Cumbria, England, UK
A large witherite crytstal being replaced by calcite and barite, on calcite. From deads in a flat in the Great Limestone, on Bounder End Cross vein.
[www.mindat.org]
I think it merits a place in the pseudogallery
avatar Re: Pseudomorphs A to C
February 25, 2011 11:16AM
My apologies to all you fans of pseudomorphs. I thought that I had more or less finished the image selection and insertion of them into the various pseudomorph articles, but found that not to be the case. Those images currently in the various pseudomorph articles are the result of selecting them from a search of mindat images for the work "after" in the image search box. I recently discovered there are many more images of interesting pseudomorphs by searching on the word "replaced" and "replacing" and I think it may take me at least another two weeks to incorporate them into the pseudomorph articles, though I wonder how many more pseudomorphs may be lurking in our vast mindat image gallery. When this is done I will start adding commentary after the various images, at least after the few that I know something about. Any comments or suggestions will be welcome though from past response I don't expect a flood of help here.

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
February 25, 2011 11:51AM
    
I sort of hate to ask this, but have you searched for pseudomorph. There are a number of descriptions that don't include either replace and after, but do contain pseudomorph..
avatar Re: Pseudomorphs A to C
February 25, 2011 11:59AM
or just pseudo
avatar Re: Pseudomorphs A to C
February 25, 2011 06:22PM
    
Hi,

this picture in the article looks more like a "sand-calcite" (maybe from fontainebleau? or morocco?) than a pseudomorph after ikaite.

©


Cheers
Stefan



Edited 1 time(s). Last edit at 02/25/2011 08:51PM by Stefan Koch.
Re: Pseudomorphs A to C
February 25, 2011 07:07PM
    
Are epimorphs a subclass of pseudomorphs? Because several of these (generally attractive and interesting) specimens appear to be epimorphic. Thought I remembered seeing a forum thread about this earlier, but couldn't find it.
EMJ
avatar Re: Pseudomorphs A to C
February 28, 2011 02:01AM
Stefan,
I think you are right. This is another I will have to look into.

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
February 28, 2011 02:03AM
Even,
Yes, I include epimorphs as a type of pseudomorph, but not encrustations of one mineral growing on top of another. The original mineral needs to have vanished.

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
March 15, 2011 11:10PM
    
Rock,

The adamite after legrandite psuedomorph has been verified with Raman Spectra! The yellow exposed cores are adamite, not legrandite! The brown coating was verified as calcite.

Hope this clears any questions,

Ron
avatar Re: Pseudomorphs A to C
March 16, 2011 03:15AM
So this makes them pseudomorphs after adamite?

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
March 16, 2011 07:18PM
    
Rock,

The shape of the calcite casts is legrandite. The contents of the casts is adamite. That makes it adamite@legrandite.

Ron
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