Mica under a "Poor Man's Polarizing Microscope"







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A rare find in the Pennsylvanian Black Shales

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On August 17th, I went on a group trip to the Starved Rock Clay Pit. I was specifically looking for some Listracanthus parts, and upon splitting open a large septarion nodule measuring roughly 2ft across, came upon what looked at first like a poorly preserved denticle. Upon returning home and examining more closely, it appeared to have segmentation. After showing photos of the specimen to Dave Carlson and Jack Wittry of ESCONI, it was identified as a rare  Tyrannophontes theridion Shram, 1969. From Wittry's book, The Mazon Ceek Fossil Fauna, "First discovered at Pit 11,  Tyrannophontes theridion was figured and described in 1969 by Shram. Subsequently, similar species were found preserved in the Pennsylvanian black shales of Iowa and Nebraska." Interestingly, nothing is mentioned of the black shales in Illinois. On a side note regarding the mysterious spiny, eel-shaped  Listracanthus that has eluded paleontologists for 150 years ,  a complete specimen has...
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Water Levels

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I thought it would be fun to periodically post water level data, since the sea levels are rising. I'll mostly focus on Lake Michigan, Great Lakes, Atlantic ocean. Here are some pictures of disappearing Juneway Beach in Chicago and a link to an article here . 2019
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Dalmanitids

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Pictured below is a very nice, large Dalmanites cephalon. A collections manager from the Field Museum brought it to a Chicago Rocks & Minerals Society meeting last year. The label says it's from the collection of Rollin Thomas Chamberlin, (1881-1948) professor of geology, University of Chicago. It was found at McCook Quarry, which unfortunately, is not accessible to collectors these days. Luckily, there are still a few localities to find Dalmanites in the Chicago area. To find one complete is extremely rare, but their disarticulated cephali and pygidia remains can be found with some luck and  persistence. Here are a few I have found. Had to glue eye back on. Below is a larger one measures about 4cm across, Glyptambon verrucosus, though not as exquisite as Mr. Chamberlin's specimen. This is how I found it after splitting open the rock. Dolostone can be tricky to work with, but with trial and error, and some luck, it can be rewarding. Had to glue it ba...
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