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Formula: (Cu,Fe)21Pb2S15
Sulphide
Crystal System: Orthorhombic
Specific gravity: 5.96 to 6.05 measured, 6.14 calculated
Hardness: 3 to 3½
Streak: Black
Colour: Black
Common impurities: Ag
Environments:
Sedimentary environments
Hydrothermal environments
Betekhtinite occurs associated with bornite,
chalcocite, chalcopyrite,
galena, silver,
celestine, anhydrite and
calcite
(HOM).
Localities:
There are two co-type localities:
the Fortschritt shaft I, Volkstedt, Eisleben, Mansfeld-Südharz, Saxony-Anhalt, Germany
and
the Ernst Thälmann Shaft, Hübitz, Siersleben, Gerbstedt, Mansfeld-Südharz, Saxony-Anhalt, Germany
At these localities betekhtinite occurs in veins cutting the Mansfeld copper
shale. It occurs in irregular masses cut by bornite,
chalcopyrite and galena, and as pure needles associated
with calcite, mostly a few tenths of a mm in diameter. Some needles have overgrowths of native
silver (AM 41.371-372). Associated minerals include
silver, galena,
chalcopyrite, chalcocite,
celestine, bornite and
anhydrite
(Mindat).
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