Sylvanite or silver gold telluride, chemical formula (Ag,Au)Te2, is the most common telluride of gold.
| Sylvanite | |
|---|---|
2Te4),_Cripple_Creek_Diatreme.jpg) Sylvanite from the Cripple Creek mining district | |
| General | |
| Category | Telluride mineral |
| Formula (repeating unit) | (Ag,Au)Te2 |
| IMA symbol | Syv[1] |
| Strunz classification | 2.EA.05 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P2/c |
| Identification | |
| Formula mass | 429.89 g/mol |
| Color | Silver-grey, silver-white |
| Crystal habit | Massive to crystalline |
| Cleavage | Perfect on the {010} |
| Fracture | Uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 1.5–2 |
| Luster | Metallic |
| Streak | Steel grey |
| Diaphaneity | Opaque |
| Specific gravity | 8.2 |
| Density | 8.1 |
| Optical properties | Anisotropic |
| Pleochroism | None |
| Ultraviolet fluorescence | None |
| References | [2][3][4] |
Properties
editThe gold:silver ratio varies from 3:1 to 1:1. It is a metallic mineral with a color that ranges from a steely gray to almost white. It is closely related to calaverite, which is more purely gold telluride with 3% silver. Sylvanite crystallizes in the monoclinic 2/m system. Crystals are rare and it is usually bladed or granular. It is very soft with a hardness of 1.5–2. It has a high relative density of 8–8.2. Sylvanite is photosensitive and can accumulate a dark tarnish if it is exposed to bright light for too long.
Occurrence
editSylvanite is found in Transylvania, from which its name is partially derived.[5] It is also found and mined in Australia in the East Kalgoorlie district. In Canada it is found in the Kirkland Lake Gold District, Ontario and the Rouyn District, Quebec. In the United States it occurs in California and in Colorado where it was mined as part of the Cripple Creek ore deposit. Sylvanite is associated with native gold, quartz, fluorite, rhodochrosite, pyrite, acanthite, nagyagite, calaverite, krennerite, and other rare telluride minerals. It is found most commonly in low temperature hydrothermal vein deposits.
Use
editSylvanite represents a minor ore of gold and tellurium. Sylvanium, an obsolete term for tellurium, derived its name from sylvanite.[6]
References
edit- ^ 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.
- ^ Sylvanite: Sylvanite mineral information and data
- ^ Sylvanite Mineral Data
- ^ "Sylvanite (Silver Gold Telluride)". Archived from the original on 2004-06-30. Retrieved 2004-06-19.
- ^ Jolyon, Ralph. "Sylvanite". mindat.org. Retrieved 18 January 2013.
- ^ Klein, Cornelis (1985), Hurlbut, Cornelius S. (ed.), Manual of Mineralogy: (after James D. Dana) (20th ed.), Albuquerque, US-NM: Wiley, p. 290, ISBN 0-471-80580-7, retrieved 2017-06-28
External links
edit
Chisholm, Hugh, ed. (1911). . Encyclopædia Britannica (11th ed.). Cambridge University Press.