The largest documented single crystals of calcite originated from Iceland, measured 7×7×2 m and 6×6×3 m and weighed somewhat 250 tons.[9][10]Calcite is a common constituent of aqueous rocks, limestone in particular, a lot of which is formed from the shells of dead marine organisms. Approximately 10% of sedimentary rock is limestone.Calcite is the primary mineral in metamorphic marble. It too occurs as a vein mineral in deposits from earnest springs, and it occurs in caverns as stalactites and stalagmites.Calcite may also be fix in volcanic or mantle-derived rocks such as carbonatites, kimberlites, or rarely in peridotites. Lublinite is a fibrous, efflorescent form of calcite.[11]Calcite is often the primary constituent of the shells of marine organisms, e.g., plankton (such as coccoliths and planktic foraminifera), the hard part of red algae, some sponges, brachiopods, echinoderms, most bryozoa, and parts of the shells of some bivalves (such as oysters and rudists). Calcite is found in spectacular form in the covered River Cave of New Mexico as mentioned above, where microorganisms are credited with infixed formations. Trilobites, which are now extinct, had unique compound eyes. They used come about calcite crystals to form the lenses of their eyes.
Calcite fluoresces blue under short wave unseeable light.
Calcite crystals inside a test of the cystoid Echinosphaerites aurantium
CategoryCarbonate mineral
chemic formulaCaCO3
Strunz classification05.AB.05
watch crystal symmetryTrigonal 32/m
Unit cella = 4.9896(2) Ã…, c = 17.061(11) Ã…; Z=6
Identification
burnishColorless or white, also gray, yellow, green,
Crystal habitCrystalline, granular, stalactitic, concretionary, massive, rhombohedral.
Crystal systemTrigonal hexagonal scalenohedral (32/m), Space Group (R3 2/c)
TwinningCommon by four twin laws
partitionPerfect on [1011] three directions with angle of 74° 55 [1]
discoverConchoidal
TenacityBrittle
Mohs scale hardness3 (defining mineral)
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