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Formula: Cu8Bi12S22
Sulphosalt, cuprobismutite homologous series group
bismuth-bearing mineral
Specific gravity: 6.35 measured, 6.451 calculated
Hardness: 4 to 5
Streak: Greyish black
Colour: Steel-grey with slight yellowish tint, tarnishes to brownish bronze
Environments
Pegmatites
Hydrothermal environments
Localities
At the Szklarska Poręba Huta granite quarry, Szklarska Poręba, Karkonosze County, Lower Silesian Voivodeship, Poland,
small bodies of granitic
pegmatite are common within the coarsely crystalline
variety of the granite. In addition to minerals typical of
granitic
pegmatites,
they contain magnetite, ilmenite,
hematite, titanite,
zircon, xenotime,
monazite, thorite,
thorogummite, yttrialite,
davidite, beryl,
gadolinite-(Y),
gadolinite-(Ce),
hingganite-(Y), epidote,
allanite, pumpellyite-(Mg),
pumpellyite-(Fe),
clinochlore, chamosite,
laumontite, chabazite,
stilbite,
ferberite-hübnerite,
scheelite, cassiterite,
molybdenite, base-metal sulphides,
emplectite, nuffieldite,
native bismuth, some
supergene minerals, and an assemblage of newly recognised
bismuth sulphosalts.
A sulphide assemblage, accompanying minor
wolframite–scheelite–cassiterite
mineralisation, crystallised from late-circulating aqueous fluids in voids within the
granite, and less frequently in typical
granitic
pegmatite in the vicinity. Besides those non-sulphide
minerals, other minerals present in the assemblage include molybdenite,
pyrrhotite, pyrite,
chalcopyrite, sphalerite,
emplectite, nuffieldite,
bismuthinite, marcasite and
native bismuth, as well as traces of
chalcocite, covellite and
malachite as common
supergene phases.
Where the samples containing hodrušite were collected, the granite
itself, as well as walls of the cavities, is in some cases mineralised with
wolframite, scheelite and
sulphides, mainly pyrite,
chalcopyrite and molybdenite;
the same minerals are found along with bismuthinite and native
bismuth in thin quartz veinlets
cutting the granite.
Emplectite and other bismuth
sulphides, such as aikinite,
friedrichite, krupkaite,
gladite, pekoite,
kupčikite, hodrušite,
cuprobismutite,
galenobismutite,
cannizzarite, cosalite,
ikunolite, joséite-A, as well as
bismite, bismutite,
powellite, koechlinite(?) and
russellite as supergene
phases, are less frequent in the assemblage.
Lamellar intergrowths of
kupčikite with hodrušite, and more infrequently hodrušite with
cuprobismutite, have been observed in all the grains studied from
Szklarska Poręba. It appears that cuprobismutite exists in the
sulphide assemblage only as nm-scale intergrowths with hodrušite
(CM 50.313-324).
At the type locality, the Hodruša-Hámre mines, Hodruša-Hámre, Žarnovica District, Banská Bystrica Region, Slovakia,
hodrušite was found In a polymetallic ore deposit of subvolcanic type, in a
quartz vein system developed in altered
pyroxenite andesite,
associated with quartz and hematite,
and locally with chalcopyrite,
pavonite and wittichenite(?).
It forms needle shaped crystals less than 1 mm in length, irregular grains, or fine-grained aggregates. Occasionaliy,
columnar and platy crystals up to 5 mm long are found. These are striated vertically
(AM 56.633, HOM).
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