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Fossiliferous Limestone: A limestone that contains obvious and abundant fossils. These are normally shell and skeletal fossils of the organisms that produced the limestone. Lithographic Limestone: A dense limestone with a very fine and very uniform grain size that occurs in thin beds which separate easily to form a very smooth surface. In the
2018-7-3 Photo and etched section of a sample of fossiliferous limestone from the Kope Formation (Upper Ordovician) near Cincinnati, Ohio, U.S. Biosparite limestone of the Brassfield Formation (Lower Silurian) near Fairborn, Ohio, U.S., showing grains mainly composed of crinoid fragments.
Limestone forms by sedimentation of coral and shells (biological limestone) or by the precipitation of calcium carbonate (sedimentary chemical limestone) from in marine waters. Limestone comes in many forms (e.g. chalk, coquina, fossiliferous, lithographic, oolitic, travertine, tufa). It can be crystalline, clastic, granular or massive ...
Rocks such as coquina are wholly composed of fossils but so-called normal limestones may be also highly fossiliferous. The sample (lower left) is from the Ordovician. Grainstone is a coarse-grained grain-supported variety that contains almost no limy mud (micrite). Limestone is defined by these two criteria: it is a sedimentary rock (1) and it is
2018-7-1 Biochemical sedimentary rocks form from sediment derived by biological processes. This typically occurs in the ocean where a variety of atoms float among the water molecules. Ions, such as calcium, magnesium, and potassium, along with trace elements like silicon, fluorine, iron and phosphorous, are ...