Oolitic Limestone: is composed mainly of calcium carbonate oolites, small spheres formed by the concentric precipitation of calcium carbonate on a sand grain or shell fragment. Oolites form by rolling back and forth on a shallow seafloor, or sometimes on a shallow lakebed, by wave action Lithographic Limestone: A dense limestone with a uniform grain size which is a very smooth surface. Oolitic limestones are whitish to cream-colored limestones composed of sand-sized (1/16 to 2 mm in size), well rounded, concentrically-layered calcite or aragonite grains called oolites (a.ka. Some are made, like sandstones, of transported and deposited grains, others are made of the skeletons or shells of animals, and others are mainly composed of very fine carbonate mud Oolitic limestone Jurassic, Gloucestershire Limestones can be made up of many different types of material. Larger grains with similar genesis are pisoids (pisoliths) oolitic limestone grain size. The term ooid is applied to grains less than 2 mm in diameter. Nucleus is usually either mineral grain or biogenic fragment. Clasts - if clastic / bioclastic then grains and / or broken or whole shell fragments visible if non-clastic / chemical then crystalline and no clasts visible Ooids are spheroidal grains with a nucleus and mineral cortex accreted around it which increases in sphericity with distance from the nucleus. Colour - variable, but generally light coloured, grey through yellow. Grain size - variable, can consist of clasts of all sizes. In the late 1700s, a printing process known as lithography (named after the stones used) was developed to reproduce images by drawing them on the stone with an oil-based ink, then using. It occurs in thin beds which separate easily to form a very smooth surface.
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