Fine oolitic agate from a fossiliferous ancient fresh water shore, in the Kramer, CA region. It is my view that these are fossil freshwater radiolaria. They are intermixed with fossil bog, and reed plants in this very localized deposit. The specimens often have calcite cemented pure beach sand stuck to them that formed a thin stratum layer of 2 inches or less (identified with infrared spectroscopy, as the calcite is not apparent). Small enough site to have been completely ignored by rockhounds, and never apparently collected. The freshwater radiolaria have simpler structures with a nucleus and spines. Unlike their oceanic counterparts with 4 layers, these have 2. That makes them very small, a sort of poppy agate. It would have been jasper with intruded iron and some clay. Outside view that caught my attention, and broken crosscut end that I buffed flat. At first I thought they might be tubes. Crosscut shows they are spheres. The nuclei of the radiolaria are the white spots. The silica nucleated on the spine exterior. That formed translucent. Literature indicates the cores of radiolaria may be chitosan, a carbon compound found in some mussel shells. It is a strong organic, leathery material. That may explain the color difference. The nuclei are too small to currently show an organic signature in infrared, but I have now acquired half the optical parts needed to hook up my infrared microscope. One more part to go, haggling off-and-on with online retailers for a decent price. Also acquired in that recent batch of equipment, extended range optics to go another 3000 cm in far-infrared. These parts are very rare, and I got lucky. I guess a slice off this is in the cards to see what the equipment can do. The microscope needs slices for the optical stage.
Posted on: Thu, 25 Dec 2014 11:32:02 +0000
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