Chemistry:Gregoryite
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| Gregoryite | |
|---|---|
 | |
| General | |
| Category | Carbonate mineral |
| Formula (repeating unit) | (Na 2,K 2,Ca)CO 3 |
| Strunz classification | 5.AA.10 |
| Crystal system | Hexagonal |
| Crystal class | Dihexagonal pyramidal (6mm) (same H-M symbol) |
| Space group | P63mc |
| Unit cell | a = 5.21 c = 6.58 [Å]; Z = 2 |
| Identification | |
| Color | Brown, milky white |
| Crystal habit | Phenocrysts in carbonatite lava |
| 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[5] with the chemical formula (Na
2,K
2,Ca)CO
3.[1][6][7] It is one of the two main ingredients of natrocarbonatite, found naturally in the lava of Ol Doinyo Lengai volcano of Arusha Region, Tanzania, and the other being nyerereite.[8]
Because of its anhydrous nature, gregoryite reacts quickly with the environment, causing the dark lava to be converted to white substance within hours.[5]
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
- ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.
- ↑ 5.0 5.1 "Gregoryite definition". Dictionary of Geology. http://www.theodora.com/geology/glossaryg.html#gregoryite. Retrieved 2011-05-21.
- ↑ Mitchell, Roger H.; Bruce A. Kjarsgaard (2010). "Experimental Studies of the System Na2CO3–CaCO3–MgF2 at 0·1 GPa: Implications for the Differentiation and Low-temperature Crystallization of Natrocarbonatite". Journal of Petrology (Oxford Journals) 52 (7–8): 1265–1280. doi:10.1093/petrology/egq069.
- ↑ Hay, Richard L (1989). "Holocene carbonatite-nephelinite tephra deposits of Oldoinyo Lengai, Tanzania". Journal of Volcanology and Geothermal Research (Elsevier (Netherlands)) 37 (1): 77–91. doi:10.1016/0377-0273(89)90114-5. Bibcode: 1989JVGR...37...77H.[|permanent dead link|dead link}}]
- ↑ "World's Coolest Lava is in Africa". Volcano Watch. USGS Hawaiian Volcano Watch. http://hvo.wr.usgs.gov/volcanowatch/2003/03_04_17.html. Retrieved 2011-05-21.
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