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Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO 3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed ...
Construction marble is a stone which is composed of calcite, dolomite or serpentine that is capable of taking a polish. [20] More generally in construction , specifically the dimension stone trade, the term marble is used for any crystalline calcitic rock (and some non-calcitic rocks) useful as building stone.
The origin of the carbonate-rich septaria is still debated. One possibility is that dehydration hardens the outer shell of the concretion while causing the interior matrix to shrink until it cracks. [ 36 ] [ 34 ] Shrinkage of a still-wet matrix may also take place through syneresis , in which the particles of colloidal material in the interior ...
These fragments mostly take the form of calcite plates ranging from 0.5 to 4 microns in size, though about 10% to 25% of a typical chalk is composed of fragments that are 10 to 100 microns in size. The larger fragments include intact plankton skeletons and skeletal fragments of larger organisms, such as molluscs , echinoderms , or bryozoans .
Calcite alabaster also is known as onyx-marble, Egyptian alabaster, and Oriental alabaster, which terms usually describe either a compact, banded travertine stone [2] or a stalagmitic limestone colored with swirling bands of cream and brown.
Limestone often contains larger crystals of calcite, ranging in size from 0.02 to 0.1 mm (0.79 to 3.94 mils), that are described as sparry calcite or sparite. Sparite is distinguished from micrite by a grain size of over 20 μm (0.79 mils) and because sparite stands out under a hand lens or in thin section as white or transparent crystals.
Draperies or curtains are thin, wavy sheets of calcite hanging downward Bacon is a drapery with variously colored bands within the sheet; Rimstone dams, or gours, occur at stream ripples and form barriers that may contain water; Stone waterfall formations simulate frozen cascades; Cave crystals
Aragonite is a carbonate mineral and one of the three most common naturally occurring crystal forms of calcium carbonate (Ca CO 3), the others being calcite and vaterite.It is formed by biological and physical processes, including precipitation from marine and freshwater environments.