I made this video with my 6 year old son. Several attempts were needed to capture it. Phenyl Salicylate (Salol) crystals melted in a test tube, then recrystallized on glass slide under microscope.
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...
The Paleozoic epicontinental seas consisted of the highest silica concentrations in comparison to the later geologic epochs of the Phanerozoic Eon. Studies show a transition from Cambrian carbonates to predominantly aragonitic marine skeletons beginning in the early Triassic Period as the ocean chemistry and earth's climate changed after the Permian Extinction. In a mutually beneficent relationship, marine organisms use the silica in oceanic waters to build their skeletal shells. Siliceous ooze forms as organisms die and sink to the seafloor. When opal silica accumulates faster than it dissolves, the skeletal fragments are recrystallized and cemented forming chert. Pictured here is a beautiful fossil coral I found along the Niagara Escarpment near Sturgeon Bay, Wisconsin. The Silurian rocks have resisted glacial meltwaters and erosion as evidenced by the extensive outcroppings, picturesque rocky beaches, and archeological ship wrecks along the peninsula. A first glance an...
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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