Gregoryite
From Infogalactic: the planetary knowledge core
| Gregoryite | |
|---|---|
| General | |
| Category | Carbonate mineral |
| Formula (repeating unit) |
(Na2,K2,Ca)CO3 |
| Strunz classification | 05.AA.10 |
| Crystal symmetry | Hexagonal dihexagonal pyramidal H-M symbol: (6mm) Space group: P 63mc |
| Unit cell | a = 5.21 Å, c = 6.58 Å; Z=2 |
| Identification | |
| Color | Brown, milky white |
| Crystal habit | Phenocrysts in carbonatite lava |
| Crystal system | Hexagonal |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.27 (calculated) |
| Optical properties | Uniaxial |
| Solubility | Soluble in water |
| References | [1][2][3] |
Gregoryite is an anhydrous carbonate mineral that is rich in potassium and sodium[4] with formula: [(Na2,K2,Ca)CO3].[1][5][6] It is one of the two main ingredients of natrocarbonatite, found naturally in the lava of Ol Doinyo Lengai volcano, the other being nyerereite.[7]
Because of its anhydrous nature, gregoryite reacts quickly with the environment, causing the dark lava to be converted to white substance within hours.[4]
Gregoryite was first described in 1980 and named after the British geologist and author John Walter Gregory (1864–1932), who studied the East African Rift Valley.[1][2] It occurs associated with nyerereite, alabandite, halite, sylvite, fluorite and calcite.[3]
References
- ↑ 1.0 1.1 1.2 Mindat.org
- ↑ 2.0 2.1 Webmineral.com
- ↑ 3.0 3.1 Handbook of Mineralogy
- ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
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