Freibergite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 3.0)
Mineral NameFreibergite
Chemical Formula(Ag,Cu,Fe)12(Sb,As)4S13
Mohs Hardness3.5
Lustermetallic
Streak Colorblack to brownish-black
Cleavagenone
Fractureconchoidal to uneven
Specific Gravity4.8
Colorssteel-gray, black
Transparencyopaque
Type LocalityReiche Zeche Mine, Himmelfahrt, Freiberg, Germany
Mineral GroupSulfosalts
Usesore of silver, collector's specimens
Associated Mineralsquartz, siderite, calcite
Rarityuncommon
Description
This specimen displays numerous dark, metallic, steel-gray to black Freibergite crystals, often with complex forms, embedded within a matrix of white granular quartz and some lighter tan crystals.
Geological Context
Freibergite typically forms in medium to low-temperature hydrothermal veins, often associated with polymetallic ore deposits rich in silver, copper, lead, and zinc.
