Kim Ellis Posted January 28, 2018 Share Posted January 28, 2018 Hi all, I acquired this piece, did not find on site. It seems to be basalt but the outer matrix is packed with sand and shell fragments. The brachiopods (I am assuming from the research I have done) are rather large, and appear in a cluster. Some of the fragments I have observed appear to be from the devonian era. I am assuming this is a steinkern vs true fossil. But the matrix is so fragile to clean it is destroying it. I am more of a rock hound than true fossil student. I have learned from some of my earlier posts last year that if the structure has been replaced by silica than it is not a true fossil ie steinkern, I believe. The matrix includes so much sand and shell fragments that it makes me question how silification works? Some of the shells, brachiopods, became irridescent as the stone absorbed moisture. Looks more like stone when it is dry.. . One of the pics that looks like brushing its teeth, has an opal in the background that I believe is the actual metamorphic process from this exact type of matrix and brachiopod by water and silica ooze. Interestingly as I have been cleaning the opal up also, it has the same structure as the outer pieces of the shell from the brachiopod, feather like. The striations in the opal also seem to be where the brachiopod foot would be... and also the richest mineral and most beautiful layer... Any ideas of what I should do with this piece to clean it or leave it alone I would love. If you have knowledge about brachiopods and opals I would love to hear that as well!! Thanks Kim Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 28, 2018 Author Share Posted January 28, 2018 Piece of matrix that fell off. Link to comment Share on other sites More sharing options...
Kane Posted January 28, 2018 Share Posted January 28, 2018 Hm. I'm not seeing a brachiopod steinkern here, but am unsure. I do see what appears to be a lot of mineral staining, though. The first picture has what appears to be striations in the lighter beige area that could be something, but it is difficult to make out. ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 28, 2018 Author Share Posted January 28, 2018 That is what appeared to be the actual shell piece when wet, irridescent...I stopped cleaning it because it was falling apart. Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 28, 2018 Author Share Posted January 28, 2018 Here are a couple of pics. One of the opal chambers that appears to me to be an open brachiopod shell? Link to comment Share on other sites More sharing options...
Kane Posted January 28, 2018 Share Posted January 28, 2018 Are you sure it's opal? Judging by this last picture, it doesn't look like a steinkern, but the inside of the shell (which would be cooler than just the steinkern ). ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 28, 2018 Author Share Posted January 28, 2018 Here is a closer picture of some stuctures, fragments. Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 28, 2018 Author Share Posted January 28, 2018 29 minutes ago, Kane said: Are you sure it's opal? Judging by this last picture, it doesn't look like a steinkern, but the inside of the shell (which would be cooler than just the steinkern ). I am positive that it is opal. The similarities between the 2 rocks is interesting. the one that I think is a steinkern has all of the flakes still in tact. The opal internalized them. They are both from volcanic matrix. I guess one is more percolation of water and storage inside the chamber of the shell. Link to comment Share on other sites More sharing options...
Kane Posted January 28, 2018 Share Posted January 28, 2018 I'll get our rock and mineral expert to say more. Paging @ynot now ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 28, 2018 Author Share Posted January 28, 2018 46 minutes ago, Kane said: I'll get our rock and mineral expert to say more. Paging @ynot now Excellent!! I will await anxiously for their relply!! Thank you!! Link to comment Share on other sites More sharing options...
ynot Posted January 28, 2018 Share Posted January 28, 2018 We will do the best We can. Basalt is a dark gray to black igneous rock that will not have fossils in it. Your rock is not basalt. It could be another type of volcanic rock. Volcanic rock will often have voids from gas bubbles in it. These voids can be filled with a multitude of secondary minerals (like quartz or opal). Some of the minerals can be iridescent like opal or fire agate. Opal or agate can coat the surface of the void and have the appearance of a shell. 1 hour ago, Kim Ellis said: Here are a couple of pics. One of the opal chambers that appears to me to be an open brachiopod shell? This picture shows a mineral filled crack that intersects the lower void, leading Me to believe that there is no fossil here. Also the shape of both voids are inconsistent for shell (brachiopod or bivalve). If it is opal and has a flaky nature then it has decomposed to some extent. I know of no way to preserve this. 1 Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 28, 2018 Author Share Posted January 28, 2018 6 minutes ago, ynot said: We will do the best We can. Basalt is a dark gray to black igneous rock that will not have fossils in it. Your rock is not basalt. It could be another type of volcanic rock. Volcanic rock will often have voids from gas bubbles in it. These voids can be filled with a multitude of secondary minerals (like quartz or opal). Some of the minerals can be iridescent like opal or fire agate. Opal or agate can coat the surface of the void and have the appearance of a shell. This picture shows a mineral filled crack that intersects the lower void, leading Me to believe that there is no fossil here. Also the shape of both voids are inconsistent for shell (brachiopod or bivalve). If it is opal and has a flaky nature then it has decomposed to some extent. I know of no way to preserve this. My question about preservation is from the other piece of basalt that looks like brachiopod steinkerns. The whole outer surface of the basalt is covered in sand and shell fragments that is very fragile. I was showing the comparison of the 2 pieces of basalt with similar mineral content and form. Thank you! Link to comment Share on other sites More sharing options...
ynot Posted January 29, 2018 Share Posted January 29, 2018 None of the rocks You have pictured here are basalt. If one is "covered with sand and shell bits" then it is not a volcanic rock. I still do not see any evidence of fossil in these pictures. Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 29, 2018 Author Share Posted January 29, 2018 Here are a couple of closer pictures of the material dry. Link to comment Share on other sites More sharing options...
ynot Posted January 29, 2018 Share Posted January 29, 2018 This looks like a poorly consolidated sandstone with some secondary mineralization. (could be a decomposing igneous rock.) I still do not see any fossil in these pictures. A steinkern is the cast of the inside of a shell, and is a fossil, but I do not see one here either. Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
Kim Ellis Posted January 29, 2018 Author Share Posted January 29, 2018 4 minutes ago, ynot said: This looks like a poorly consolidated sandstone with some secondary mineralization. (could be a decomposing igneous rock.) I still do not see any fossil in these pictures. A steinkern is the cast of the inside of a shell, and is a fossil, but I do not see one here either. Thank you so much for your time. I grew up collecting fossilized colony coral and other fossils from Grand Traverse Bay, so maybe I am infusing this knowledge into what I am seeing with what I saw over many years collecting along the beaches. Thank you for looking and giving me your opinion! Kim Link to comment Share on other sites More sharing options...
ynot Posted January 29, 2018 Share Posted January 29, 2018 Just now, Kim Ellis said: Thank you for looking and giving me your opinion! You are welcome, hope it helped. Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
Recommended Posts