Peat Burns Posted February 27, 2019 Share Posted February 27, 2019 Not a fossil (although in some contexts, a pseudofossil), but I cut and hand-polished a piece of oolitic limestone this evening. These are nice, big, ooids (pisoids in this case), and one can easily see the layering. I thought some might like to see the results (scale in mm). 7 Link to comment Share on other sites More sharing options...
FranzBernhard Posted February 27, 2019 Share Posted February 27, 2019 That was worth the effort, nice rock! Where is it from and how old is it? Franz Bernhard 1 Link to comment Share on other sites More sharing options...
Peat Burns Posted February 27, 2019 Author Share Posted February 27, 2019 9 minutes ago, FranzBernhard said: That was worth the effort, nice rock! Where is it from and how old is it? Franz Bernhard Thank you, Franz. Unfortunately, I don't know the location. I've had that piece for 40 years since I was a young boy. It came on a cardboard with various fossils that I bought from the gift store at the Field Museum of Natural History in Chicago. We were discussing oolite formation this evening and it reminded me of that piece, so I decided it was a good time to cut into it and have a closer look Here is a pic of another one I took this evening from the Burlington Limestone Formation of Mediapolis Iowa (Mississippian). Or at least I believe this is oolite. If it is, it's not as well developed. They are only about a mm in size with no obvious layers - just a single layer around the "seed" clast. 2 Link to comment Share on other sites More sharing options...
FranzBernhard Posted February 27, 2019 Share Posted February 27, 2019 Also a nice one, could be genetically a little bit different, but I would call it also oolitic. Can you find something about such rocks in the 7 minutes ago, Peat Burns said: Burlington Limestone Formation of Mediapolis Iowa (Mississippian) ? Franz Bernhard 1 Link to comment Share on other sites More sharing options...
Peat Burns Posted February 27, 2019 Author Share Posted February 27, 2019 4 minutes ago, FranzBernhard said: Also a nice one, could be genetically a little bit different, but I would call it also oolitic. Can you find something about such rocks in the ? Franz Bernhard It does appear that oolite is documented there: "Summary: btw. p. 90 and 140. Encrinital group of Burlington (also called Burlington beds). In descending order: white crystalline and semi-oolitic limestones; brown and flesh-colored encrinital limestones; brown earthy crinoidal limestones with crystalline specks; band of cellular buff magnesium limestone; oolitic limestone; dark-gray argillaceous limestones. Overlies argillo-calcareous group. Separated from overlying Keokuck cherty limestones by brown Encrinital limestones alternating with bands of chert, as near Hannibal [Missouri]. [According to later reports the cherty beds of passage are Keokuck cherty limestones of Owen.] Source: US geologic names lexicon (USGS Bull. 896, p. 298-299)." 1 Link to comment Share on other sites More sharing options...
FranzBernhard Posted February 27, 2019 Share Posted February 27, 2019 2 minutes ago, Peat Burns said: oolitic limestone Thanks! Franz Bernhard Link to comment Share on other sites More sharing options...
Ludwigia Posted February 27, 2019 Share Posted February 27, 2019 Thanks for posting these informative photos. Interesting how each is different from the other. No uniformity there other than to the naked eye. 1 Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Peat Burns Posted February 27, 2019 Author Share Posted February 27, 2019 6 minutes ago, Ludwigia said: Thanks for posting these informative photos. Interesting how each is different from the other. No uniformity there other than to the naked eye. I'm glad you enjoy them! While not fossils, they are great palaeoenvironmental indicators 1 Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted March 1, 2019 Share Posted March 1, 2019 Beautiful photos. Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
abyssunder Posted March 1, 2019 Share Posted March 1, 2019 Pretty nice ooids and pisoids! I can add just a polished sphere bought from China, to sustain their worldwide existence. 1 " We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. " Thomas Mann My Library Link to comment Share on other sites More sharing options...
Peat Burns Posted March 1, 2019 Author Share Posted March 1, 2019 2 minutes ago, abyssunder said: Pretty nice ooids and pisoids! I can add just a polished sphere bought from China, to sustain their worldwide existence. Now that is cool! Thanks for posting it. Link to comment Share on other sites More sharing options...
Peat Burns Posted March 1, 2019 Author Share Posted March 1, 2019 22 minutes ago, Tidgy's Dad said: Beautiful photos. Thanks, Adam Link to comment Share on other sites More sharing options...
sTamprockcoin Posted March 10, 2019 Share Posted March 10, 2019 We have oolitic chert around here (Mines Member of the Gatesburg Formation) black ooids in white matrix, white in black, white in gray. It's very hard and can be polished if it's not iron stained or cracked. It's not considered biologic in origin. “Beautiful is what we see. More beautiful is what we understand. Most beautiful is what we do not comprehend.” N. Steno Link to comment Share on other sites More sharing options...
fossilnut Posted March 10, 2019 Share Posted March 10, 2019 19 hours ago, sTamprockcoin said: It's not considered biologic in origin. Could you provide further information on its origin? While i have done some reading about oolite, I can't fully understand your meaning. I have heard of ooids formed in the Great Salt Lake, Utah around brine shrimp fecal matter. I just find them fascinating and want to learn more and hopefully find some myself (or trade for some). Link to comment Share on other sites More sharing options...
sTamprockcoin Posted March 11, 2019 Share Posted March 11, 2019 Sorry for causing you confusion. Not all oolites are the same thing. Your oolitic limestone IS biological in origin. The oolitic chert of the Gatesburg Formation is considered a chemical sedimentary formation. Several papers have been written and our mineral club has had presentations on this. I'll see if I can dig up the info. Here's a pic of an almost volleyball sized chunk of oolitic chert. 1 “Beautiful is what we see. More beautiful is what we understand. Most beautiful is what we do not comprehend.” N. Steno Link to comment Share on other sites More sharing options...
fossilnut Posted March 11, 2019 Share Posted March 11, 2019 Thanks. I would be interested if its not too much trouble. Nice specimen. Link to comment Share on other sites More sharing options...
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