Tjbfossils Posted Wednesday at 11:11 PM Share Posted Wednesday at 11:11 PM Hello! In my area I find many calcified fossils. One of the problems is they are in dense limestone nodules. Acetic acid dissolves the fossils so I can’t do that and mechanical prep is too difficult with the tough stone and also has destroyed some of the specimens from fracturing. Is there a chemical means to remove the limestone and not damage the fossils? They are mostly cephalopods. Link to comment Share on other sites More sharing options...
DPS Ammonite Posted Wednesday at 11:20 PM Share Posted Wednesday at 11:20 PM No. Acid dissolves both “calcified fossils” and limestone. The best that you can do is cutting and polishing the rock; you might have a great cross section. My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Tjbfossils Posted Thursday at 12:09 AM Author Share Posted Thursday at 12:09 AM 47 minutes ago, DPS Ammonite said: No. Acid dissolves both “calcified fossils” and limestone. The best that you can do is cutting and polishing the rock; you might have a great cross section. I have cut them and got a few nice cross sections but they are deep in the concretions so it’s a gamble whether you cut it laterally and get a nice section or just a strange cut. I was thinking maybe there were other chemicals besides acids like bases that could remove the limestone but preserve the calcite Link to comment Share on other sites More sharing options...
DPS Ammonite Posted Thursday at 01:27 AM Share Posted Thursday at 01:27 AM (edited) 1 hour ago, Tjbfossils said: I was thinking maybe there were other chemicals besides acids like bases that could remove the limestone but preserve the calcite Limestone is mainly calcite and is dissolved by acid. Both are similarly unaffected by most common bases. Edited Thursday at 01:29 AM by DPS Ammonite My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Isotelus2883 Posted Thursday at 04:05 AM Share Posted Thursday at 04:05 AM Have you tried freeze-thaw or heating and then rapidly cooling them? Link to comment Share on other sites More sharing options...
DPS Ammonite Posted Thursday at 05:16 AM Share Posted Thursday at 05:16 AM (edited) 1 hour ago, Isotelus2883 said: Have you tried freeze-thaw or heating and then rapidly cooling them? If that easily worked, then Mother Nature would have released lots of calcitic fossils from pure limestone. If the matrix has lots of mud in the limestone, I have heard that lye flakes may selectively break up the mud, but not touch the calcite. In other words, you may be able to extract calcitic fossils from muddy marls. Edited Thursday at 05:39 AM by DPS Ammonite My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Tjbfossils Posted Thursday at 05:20 PM Author Share Posted Thursday at 05:20 PM 13 hours ago, Isotelus2883 said: Have you tried freeze-thaw or heating and then rapidly cooling them? I have and it just cracks along calcite veins within the concretions. I should’ve added that they are also filled with calcite 1 Link to comment Share on other sites More sharing options...
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