Guguita2104 Posted November 28, 2015 Share Posted November 28, 2015 I found these today and I'm not sure if they are petrified wood or just mineral/geological .The layers are Lower/Middle Jurassic and belong to the greatest Karst in the Iberian Peninsula(if I'm not wrong) : Serra d'Aire e Candeeiros and they are very rich in brachiopods, bivalves and ammonites. Can someone explain me what they are?Regards, 1- 2- Link to comment Share on other sites More sharing options...
Auspex Posted November 28, 2015 Share Posted November 28, 2015 Are they silica, or calcite? "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Guguita2104 Posted November 28, 2015 Author Share Posted November 28, 2015 I'm not very sure (I think it's silica), but in contact with water it began to crumble. Link to comment Share on other sites More sharing options...
PaleoWilliam Posted November 28, 2015 Share Posted November 28, 2015 I don't think it's wood. Link to comment Share on other sites More sharing options...
Guguita2104 Posted November 28, 2015 Author Share Posted November 28, 2015 Thanks Paleowilliam. Link to comment Share on other sites More sharing options...
Ludwigia Posted November 28, 2015 Share Posted November 28, 2015 (edited) What you've got there is banded travertine, or kalksinter, as we call it in German. A form of calcite. It is extremely common in karst sediments. That's what limestone stalactites and stalagmites are mostly made of. Looks nice when cut and polished. Edited November 28, 2015 by Ludwigia Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
howard_l Posted November 30, 2015 Share Posted November 30, 2015 Looks like Travertine to me, if it won't fizz with vinegar it could be barite. Howard_L http://triloman.wix.com/kentucky-fossils Link to comment Share on other sites More sharing options...
Agos1221 Posted November 30, 2015 Share Posted November 30, 2015 I am afraid it is just a mineral, possibly gypsum? I neglected to read the comments above to give an unbiased answer Link to comment Share on other sites More sharing options...
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