Polybasite
[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]IMA symbol Plb[1] Strunz classification 2.GB.15 Crystal system Monoclinic and trigonal polytypes Crystal class Prismatic (2/m)
(same H-M symbol) Space group C2/c Identification Colour steel black Cleavage poor on (001) Fracture uneven Mohs scale hardness 1.5–2 Lustre metallic, adamantine or glimmering Streak black with reddish tint Specific gravity 6–6.2 References [2][3][4][5]
(same H-M symbol)
Polybasite is a sulfosalt mineral of silver, copper, antimony and arsenic. Its chemical formula is [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4].
It forms black monoclinic crystals (thin, tabular, with six corners) which can show dark red internal reflections. It has a Mohs hardness of 2.5 to 3. It is found worldwide and is an ore of silver. The name comes from the number of base metals in the mineral.
Images
- Unusual polybasite specimen from Mayo Mining District, Yukon Territory, Canada.
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.
- ^ Polybasite: mindat.org
- ^ Webmineral.com
- ^ "Handbook of Mineralogy" (PDF). Archived from the original (PDF) on 2016-03-03. Retrieved 2011-05-16.
- ^ Rudolf Dǔd'a and Luboš Rejl (1990). Minerals of the World. Arch Cape Press. p. 40. ISBN 0-517-68030-0.
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