Dolomite (mineral)
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.
| Dolomite | |
|---|---|
Dolomite (white) on talc | |
| General | |
| Category | Carbonate minerals |
| Formula (repeating unit) | CaMg(CO3)2 |
| IMA symbol | Dol |
| 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 | |
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