From Wikipedia, the free encyclopedia
Calcite is a carbonate mineral an the maist stable polymorph o calcium carbonate (CaCO3). The ither polymorphs is the meenerals aragonite an vaterite. Aragonite will chynge tae calcite at 380–470 °C,[5] an vaterite is even less stable.
| Calcite | |
|---|---|
| |
| General | |
| Category | Carbonate mineral |
| Formula (repeatin unit) | CaCO3 |
| Strunz clessification | 05.AB.05 |
| Creestal seestem | Trigonal hexagonal scalenohedral (32/m), Space Group (R3 2/c) |
| Space group | Trigonal 32/m |
| Unit cell | a = 4.9896(2) Å, c = 17.0610(11) Å; Z=6 |
| Identification | |
| Colour | Colourless or white; can be gray, yellae or green. |
| Creestal habit | Crystalline, granular, stalactitic, concretionary, massive, rhombohedral. |
| Twinnin | Common bi fower twin laws |
| Cleavage | Perfect on [1011] three directions wi angle o 74° 55'[1] |
| Fractur | Conchoidal |
| Tenacity | Brickle |
| Mohs scale haurdness | 3 (definin mineral) |
| Skinkle | Vitreous tae pearly on cleavage surfaces |
| Streak | White |
| Diaphaneity | Transparent tae translucent |
| Speceefic gravity | 2.71 |
| Optical properties | Uniaxial (-) |
| Refractive index | nω = 1.640 – 1.660 nε = 1.486 |
| Birefringence | δ = 0.154 – 0.174 |
| Solubility | Soluble in dilute acids |
| Ither chairacteristics | Mey fluoresce reid, blae, yellae, an ither colours unner aither SW an LW UV; phosphorescent |
| References | [2][3][4] |
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