mikecable Posted March 25, 2012 Author Share Posted March 25, 2012 Peroxide is oxidizing the organic matter in the shale or any clay in a limestone, or just the "dirt" covering your sample. Makes sense. The Jacksboro material I've found mostly came from just beneath the Jacksboro Limestone cap, with the most productive zone seeming to be about four meters up, a black to dark grey shale, with abundant phospate and siderite nodules. As both collecting trips occurred just after moderate to heavy rains, anything I touched immediately became smeared with a coating of mud, no matter how careful I was. I believe the peroxide is popping the mud off, as well as oxidizing some of the organic material in the shale. Link to comment Share on other sites More sharing options...
mikecable Posted March 25, 2012 Author Share Posted March 25, 2012 (edited) Based on the huge can of worms I opened up with some other brachiopods from this site--Marginifera sp.--I'm not even going to venture a guess at this time. But the fossilization of these specimens gives me pause. Unlike the other Marginifera sp., these are preserved as only as the top half of the valve. I don't know enough to say whether they are cast, molds or examples of mineralization. I find them all in the same zone of the Finis Shale, or washed out upon the basal flats. They all have a glint or sheen to them that I can only describe as being like steel. I'm more of an English major guy than paleontologist so I've been searching for the right phrase to emphasize this aspect of my picture. My first thought was the steel of an old rifle receiver or barrel, well-cared for, but missing the bluing. That was not quite right. My next thought was an old Chicago Cutlery knife blade, high-carbon, but well cared for. Still not right. Finally I thought of highly burnished railroad tracks. Still in use, but still oxidizing. I met this dame once. Icy blue eyes,spiked platinum blonde hair and a heart like railroad steel. She.... Oops. Wrong forum. But these fossils definitely look like railroad steel. Upper half of the valves only, well preserved. Thoughts? Edited March 25, 2012 by mikecable 1 Link to comment Share on other sites More sharing options...
mikecable Posted March 25, 2012 Author Share Posted March 25, 2012 I've found many that looked similar at Mineral Wells Fossil Park. I've found some, but not as many at Jacksboro, but when I find them I find many that look similar. But this is the only one I've found this large, relatively complete, and fairly well preserved. Link to comment Share on other sites More sharing options...
mikecable Posted March 25, 2012 Author Share Posted March 25, 2012 I'm fairly sure on ID. Just a pretty pic--at least for me. Link to comment Share on other sites More sharing options...
Auspex Posted March 25, 2012 Share Posted March 25, 2012 Mother-of Pearlish? Probably nacre, or a pseudomorph thereof. From Wikipedia: "Nacre appears iridescent because the thickness of the aragonite platelets is close to the wavelength of visible light. This results in constructive and destructive interference of different wavelengths of light, resulting in different colors of light being reflected at different viewing angles." "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...
mikecable Posted March 25, 2012 Author Share Posted March 25, 2012 Mother-of Pearlish? Probably nacre, or a pseudomorph thereof. From Wikipedia: "Nacre appears iridescent because the thickness of the aragonite platelets is close to the wavelength of visible light. This results in constructive and destructive interference of different wavelengths of light, resulting in different colors of light being reflected at different viewing angles." A guess perhaps a pseudomorph. This does not look like mother-of-pearl. It has the iridescent appearance, but doesn't appear pearl-like. Not even to my limited experience like black pearl, but that may be the answer. Link to comment Share on other sites More sharing options...
erose Posted March 26, 2012 Share Posted March 26, 2012 Regarding post #52. I have a handful of those as well. I just call 'em shiny. I'm still trying to sort out the differences between Hystriculina wabashensis and Kozlowskia splendens. But anyone who can shed light please do! Mckenzie & McLeod (2003) only list Hystriculina texana for Finis Shale at Jacksboro but I believe the book actually illustrates Retaria lalsallensis. So in a nutshell I'm perplexed. The photos of Marginifera wabashensis in IFNA look like these. Link to comment Share on other sites More sharing options...
Fruitbat Posted March 26, 2012 Share Posted March 26, 2012 I've picked up quite a number of the 'shiny' little brachiopods in the Jacksboro area as well. My best educated guess is Kozlowskia splendens and, so far as I can tell, they ALL have the nacreous appearance. -Joe Illigitimati non carborundum Fruitbat's PDF Library Link to comment Share on other sites More sharing options...
Herb Posted March 26, 2012 Share Posted March 26, 2012 I really like the Straparollus. I also would like to see any unknowns from the Penn. marine. "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
mikecable Posted March 26, 2012 Author Share Posted March 26, 2012 I really like the Straparollus. I also would like to see any unknowns from the Penn. marine. I really like them as well. When they are wet and in the sun the colors pop like a beautiful piece of hand-dyed African tapestry, including some gold iridescence that probably indicates pyritization. As an aside not really relating to your comment on the Straparollus, my sixth grade students truly enjoyed, and hopefully learned from a 30 to 45 minute discussion of this topic today. Mostly we looked at the pics, and discussed from my point of view the various hypotheses the forum came up with on IDs. We are working on geology right now, and more specifically have gone from "earth processes" to "plate tectonics". But I've been using my various expeditions as a key point to keep their interest. I'm doing my best to segue into taxonomy, which will be my focus for the next to last 3 week period. They are learning that science is not always multiple choice, much less true or false. Had I known that at the age of 16, I would have been much more likely to major in science. But I was taught that all, or almost all the problems had been solved. So I made the decision, at about that age, to investigate novels and poetry. I don't regret the decision. There is still a part of me that want's to retire as a great "naturalist" writer. They see the folks on this forum as scientists. I've had no cause to tell them otherwise. with that one exception, that somehow involve hundreds of skulls and teeth, and fossils But that's a different story, and it went poof. Rightfully so, but it would have made a nice example of theories that go poof. Yous guys, y'all, you all, you 'uns, my home-boys, my brothers and sisters on the forum. My kids believe you are all pure D, government approved scientists. And this is a good thing. Thanks. Link to comment Share on other sites More sharing options...
Herb Posted March 28, 2012 Share Posted March 28, 2012 A very nice story about your students.I'll bet you're a good teacher. I have taught some middle school Earth science myself long ago. This is just a general comment, and in no way a rebuke to you. I would say from what I have read in these topics that many of the people responding to the topics are scientists, some with a degree, some amateur. Some of the knowledge exhibited in these forum topics is AWESOME (realizing this is an overused word in todays society, it still applies). I believe that there are people on this forum that could probably hold their own with any paleontologist in their field. You might also tell your kids that most of the important historical finds in paleontology were by non-scientists, just people with an imagination and a thirst for knowledge and didn't mind getting dirt under their nails. A quest for knowledge is more important than a degree. Have to stop, preaching again! ps, I have some pix of KY Penn. marine in my gallery if you want to compare. By the way, Mike, I think you write a great posting, you have a beautiful way with words "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
Auspex Posted March 28, 2012 Share Posted March 28, 2012 ...By the way, Mike, I think you write a great posting, you have a beautiful way with words A scientist with the soul of a philosopher. "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...
Indiana Posted March 28, 2012 Share Posted March 28, 2012 Gorgeous fossils. How are you cleaning these? Link to comment Share on other sites More sharing options...
Herb Posted March 28, 2012 Share Posted March 28, 2012 Those productids look almost like they're preserved in Hematite? "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
mikecable Posted March 28, 2012 Author Share Posted March 28, 2012 A scientist with the soul of a philosopher. Thanks. Many years ago, (1980 to be specific), I turned from science to the arts. Surprisingly because I derived a fairly complicated equation on a chalk board. Had an epiphany. Post-epiphany I was singing " Que sera, sera". Gorgeous fossils. How are you cleaning these? Sized sieves to lose as few as possible. These are mostly small, and due to collecting conditions were a muddy mess the second I picked them up. Wash and rinse. Wash and rinse. Then repeat the cycle with 3% hydrogen peroxide--the buck a bottle sort. Let the bubbling stop--sometime 48 hours--wash and rinse--then repeat. I've been washing some of these fossils for more than a month. I'm probably guilty of hubris, but a few of these are cleaning up nice enough to go to church. One or two might make it to the wedding. Now I just need to learn how to take pictures. Those productids look almost like they're preserved in Hematite? I think you've nailed it. I'm just not sure it has been named. Hematic pearlescant? Link to comment Share on other sites More sharing options...
Missourian Posted March 28, 2012 Share Posted March 28, 2012 Is it possible that the metallic luster of the marginiferids could result from a finely layered shell structure preserved within the calcite? Context is critical. Link to comment Share on other sites More sharing options...
Indiana Posted March 28, 2012 Share Posted March 28, 2012 I'm probably guilty of hubris, but a few of these are cleaning up nice enough to go to church. One or two might make it to the wedding. Thanks for the cleaning tips. I'm not sure being moved by the beauty nature has created could be considered hubris. Of course, I don't know you, it could be hubris... Link to comment Share on other sites More sharing options...
Herb Posted March 28, 2012 Share Posted March 28, 2012 FYI, don't use peroxide on pyritized specimens they will "rust" fast. Tried it last night to fine tune some Dev. brachs, going to have to do some restorative work on the sheen. Live and learn. "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
Herb Posted April 2, 2012 Share Posted April 2, 2012 Sometimes boiling the shale with a little TSP or Dishwasher granules in the water will sometimes help break up the shale. "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
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