Chemistry:Freibergite

From HandWiki
Freibergite
Freibergite-258726.jpg
General
CategorySulfosalt minerals
Formula
(repeating unit)
Cu12Sb4S13
Strunz classification2.GB.05
Crystal systemCubic
Crystal classHextetrahedral (43m)
H-M symbol: (4 3m)
Space groupI43m
Identification
Formula mass1,929.46 g/mol
ColorSteel gray to black
Crystal habitmassive to well formed crystals
CleavageNone
FractureUneven
Mohs scale hardness3 12 - 4
|re|er}}Metallic
Streakreddish black
DiaphaneityOpaque

Freibergite is a complex sulfosalt mineral of silver, copper, iron, antimony and arsenic with formula (Ag,Cu,Fe)
12
(Sb,As)
4
S
13
. It has cubic crystals and is formed in hydrothermal deposits. It forms one solid solution series with tetrahedrite and another with argentotennantite. Freibergite is an opaque, metallic steel grey to black and leaves a reddish-black streak. It has a Mohs hardness of 3.5 to 4.0 and a specific gravity of 4.85 - 5. It is typically massive to granular in habit with no cleavage and an irregular fracture.

The mineral was first described in 1853 from an occurrence in the silver mines of the type locality at Freiberg, Saxony.

References