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FOSSIL LIMESTONE #2 (detail) Biomicrite Go on to: #1 | #2 | #3 | #4 
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Composition
Micrite = lime mud; CaCO3, the mineral calcite surrounding and supporting skeletons, mostly of crinoids (white fragments) and brachiopods (black, curved fragments), although bryozoans and other organisms are present.Micrite is the equivalent of clay (rock = shale) in clastics. See Origin of Micrite for more details. |
Description
Saw cut slab of limestone, wet with water before being photographed. Black and white objects are cut sections of fossils. The white pieces are mostly crinoid stem fragments. Crinoids stems are cylindrical columns made up of discs strung together like a stack of poker chips. Sometimes they appear round when the stem has been cut across the axis, while longitudinal cuts are rectangular.The curved black fossils are cross sections through brachiopods or trilobites. The light gray areas are the unform, dense micrite. |
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