Dolomite (mineral)

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Dolomite
Dolomite (white) on talc
General
Category	Carbonate minerals
Formula (repeating unit)	CaMg(CO3)2
IMA symbol	Dol[1]
Strunz classification	5.AB.10
Crystal system	Trigonal
Crystal class	Rhombohedral (3) H–M symbol: (3)
Space group	R3
Unit cell	a = 4.8012(1), c = 16.002 [Å]; Z = 3
Identification
Color	White, grey to pink, reddish-white, brownish-white; colourless in transmitted light
Crystal habit	Tabular crystals, often with curved faces, also columnar, stalactitic, granular, massive.
Twinning	Common as simple contact twins
Cleavage	3 directions of cleavage not at right angles
Fracture	Conchoidal
Tenacity	Brittle
Mohs scale hardness	3.5–4.0
Luster	Vitreous to pearly
Streak	White
Specific gravity	2.84–2.86
Optical properties	Uniaxial (−)
Refractive index	nω = 1.679–1.681 nε = 1.500
Birefringence	δ = 0.179–0.181
Solubility	Poorly soluble in dilute HCl
Other characteristics	May fluoresce white to pink under UV; triboluminescent. Ksp values vary between 10−19 and 10−17
References	[2][3][4][5][6]

Dolomite (/ˈdɒl.əˌmaɪt, ˈdoʊ.lə-/) is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally CaMg(CO₃)₂. The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite (see Dolomite (rock)). An alternative name sometimes used for the dolomitic rock type is dolostone.