| Lyonsite | |
|---|---|
| General | |
| Category | Vanadate mineral | 
| Formula (repeating unit) | Cu3Fe+34(VO4)6 | 
| IMA symbol | Lyo[1] | 
| Strunz classification | 8.AB.40 | 
| Crystal system | Orthorhombic | 
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | 
| Space group | Pmcn | 
| Unit cell | a = 10.29, b = 17.2 c = 4.91 [Å]; Z = 2 | 
| Identification | |
| Color | Black; creamy white in reflected light in polished section | 
| Crystal habit | As euhedral flattened lath shaped crystals | 
| Cleavage | Good on {001} | 
| Tenacity | Brittle | 
| Luster | Metallic | 
| Streak | Dark gray | 
| Diaphaneity | Opaque | 
| Specific gravity | 4.215 calculated | 
| References | [2][3][4] | 
Lyonsite (Cu3Fe+34(VO4)6) is a rare black vanadate mineral that is opaque with a metallic lustre. It crystallizes in the orthorhombic crystal system. Lyonsite often occurs as small tabular typically well formed crystals. Lyonsite has a good cleavage and a dark gray streak.
Lyonsite occurs as a sublimate in volcanic fumaroles. It is often associated with howardevansite and thenardite.[2] It was first described in 1987 for an occurrence on the Izalco volcano, El Salvador. It was named for mineralogist John Bartholomew Lyons (1916–1998) of Dartmouth College.[3] It has also been reported from a mine dump in the Lichtenberg Absetzer Mine of Thuringia, Germany.[4]
References
- ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- 1 2 Mineral Handbook
- 1 2 Webmineral
- 1 2 Mindat
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