Frank Menser Posted November 18, 2009 Share Posted November 18, 2009 Ok...this being a forum about Fossils, how about Fossils of minerals? So cough em up, let's see your Psuedomorphic Trophies! First an obvious one. A nice eight inch chunk of Tigereye (quartz after asbestos) And from Rumania, Chalcedony after Calcite. Be true to the reality you create. Link to comment Share on other sites More sharing options...
barefootgirl Posted November 18, 2009 Share Posted November 18, 2009 Wow I never even thought of fossilized minerals. I wouldn't know what to look for. Thats really cool Frank. In formal logic, a contradiction is the signal of defeat: but in the evolution of real knowledge, it marks the first step in progress toward victory. Alfred North Whithead 'Don't worry about the world coming to an end today. It's already tomorrow in Australia!' Link to comment Share on other sites More sharing options...
Frank Menser Posted November 18, 2009 Author Share Posted November 18, 2009 It's really an under appreciated part of mineral collecting and more common than most are aware of. Some typical examples of replaced minerals are are Halite, Calcite, Azurite and (Below) Pyrite-in this case replaced by Limonite. Be true to the reality you create. Link to comment Share on other sites More sharing options...
barefootgirl Posted November 18, 2009 Share Posted November 18, 2009 Im sorry if this is a stupid question but how can you tell it was one mineral replaced by another. In formal logic, a contradiction is the signal of defeat: but in the evolution of real knowledge, it marks the first step in progress toward victory. Alfred North Whithead 'Don't worry about the world coming to an end today. It's already tomorrow in Australia!' Link to comment Share on other sites More sharing options...
Bear Posted November 18, 2009 Share Posted November 18, 2009 (edited) Minerals each come from a distinct crystal system so all crystal specimens of a particular mineral should have the same shape. Sometimes they don't though, like the calcite crystals that are shaped like quartz crystals. The quartz went away after the crystals formed and was replaced by the calcite giving us quartz crystal shaped calcite, for example. EDIT: You can then tell this happened with routine identification of the specimen in hand, like hardness, colour and specific gravity. Edited November 18, 2009 by Bear Link to comment Share on other sites More sharing options...
TourmalineGuy Posted November 18, 2009 Share Posted November 18, 2009 To add to Bears explanation: When you have a pseudomorph, you can narrow down what came before based on the chemical structure of the current mineral. Certain elements will replace atoms of similar size, resulting in predictable pseudomorphs. Also, often pseudmorphs will be replaced from the outside inward. This can result in an outside "shell" that is a pseudomorph, with the original mineral in the center. Whats very tough to identify are pseudomorphs of pseudomorphs... Sorry, I don't have any pseudomorph pictures:( Link to comment Share on other sites More sharing options...
barefootgirl Posted November 19, 2009 Share Posted November 19, 2009 Ihank you for explaining that to me guys, I was thinking it was probably something to do with structure. In formal logic, a contradiction is the signal of defeat: but in the evolution of real knowledge, it marks the first step in progress toward victory. Alfred North Whithead 'Don't worry about the world coming to an end today. It's already tomorrow in Australia!' Link to comment Share on other sites More sharing options...
Bear Posted November 19, 2009 Share Posted November 19, 2009 ..Whats very tough to identify are pseudomorphs of pseudomorphs... I hadn't even thought of that! It would indeed be most difficult to ID in that case.Your are most welcome, of course, ma'am. Link to comment Share on other sites More sharing options...
Frank Menser Posted November 19, 2009 Author Share Posted November 19, 2009 (edited) Yes it can get very confusing. If you happen by the Aurora Museum, there is a large Psuedomorph I donated of Calcite sand after Calcite, which sounds weird. But what happens is the orrigional Calcite is disolved and the empty space is filled by Calcite rich sand. This process can happen over and over so the orrigional shape of the crystals may be altered or lost. This, by the way is one reason why vertebrate fossils are so rare in S. Florida. After a couple of times through the process they are unrecogniseable. Note the center of this bone which is replaced by a mixture of Calcite crystals and sand. If left to nature the outter bone would eventually disappear making a cast that is not very much like the orrigional bone. It is common to find in S. Florida tubes of Calcite crystals that have replaced bone or coral with nothing left but a crystaline druse. Edited November 19, 2009 by Frank Menser Be true to the reality you create. Link to comment Share on other sites More sharing options...
Bill Posted November 20, 2009 Share Posted November 20, 2009 (edited) Mudstone pseudomorphs after Halite. Specimen width 45mm. Aust Cliff, South Gloucestershire (Bristol; Avon), England, UK Edited November 20, 2009 by Bill KOF, Bill. Welcome to the forum, all new members www.ukfossils check it out. Link to comment Share on other sites More sharing options...
Frank Menser Posted November 24, 2009 Author Share Posted November 24, 2009 Mudstone pseudomorphs after Halite. Specimen width 45mm. Aust Cliff, South Gloucestershire (Bristol; Avon), England, UK I like it... Here is the Calcite Psuedo I mentioned above. It weighs a whopping thirty lbs! Be true to the reality you create. Link to comment Share on other sites More sharing options...
zoup Posted November 25, 2009 Share Posted November 25, 2009 Hi all. Here is a field photo of a piece of Manganese Dendrite that I found the last time I was up to the Camp horne fossil location in Pittsburgh Pa. I also found some nice Calcite crytals/pieces. Cleare skies to all and good hunting Paul. I have a lot of the calcite if any body would like some. Link to comment Share on other sites More sharing options...
Frank Menser Posted November 25, 2009 Author Share Posted November 25, 2009 Wow! That is quite a site! Be true to the reality you create. Link to comment Share on other sites More sharing options...
Bear Posted November 25, 2009 Share Posted November 25, 2009 Yeah, I was liking it too, Frank. Maybe with lunch and a beer and a couple of hours....... Link to comment Share on other sites More sharing options...
dirtdauber Posted November 26, 2009 Share Posted November 26, 2009 "Also, often pseudmorphs will be replaced from the outside inward. This can result in an outside "shell" that is a pseudomorph, with the original mineral in the center." Limonite after pyrite on quartz (cubes in matrix and loose). Second photo shows remnants of the original mineral, pyrite, in the interior of the crystal, as described by TourmalineGuy. Link to comment Share on other sites More sharing options...
micropterus101 Posted December 24, 2009 Share Posted December 24, 2009 Here is GLENDONITE Calcite pseudomorph after IKAITE concretion from Washington state. I cut and polished it. Looks like a ? fossil crabs website Link to comment Share on other sites More sharing options...
fig rocks Posted December 25, 2009 Share Posted December 25, 2009 That's a cool piece micro! Link to comment Share on other sites More sharing options...
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