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Formula: Cu1.4Pb2.4Bi2.4Sb0.2S7
Sulphosalt, bismuth- and antimony-
bearing mineral; antimony appears to be an essential component for the
stabilisation of nuffieldite
Crystal System: Orthorhombic
Specific gravity: 7.01 measured, 7.21 calculated
Hardness: 3½ to 4
Streak: Greyish black
Colour: Grey, steel grey, greyish green, reddish brown
Environments
Localities
At the type locality, the British Columbia Molybdenum Ltd. mine, Patsy Creek, Kitsault, Alice Arm, Skeena Mining
Division, British Columbia, Canada, the stock is composite,
and consists of granodiorite,
quartz
diorite, alaskite,
granodiorite porphyry
and related breccia. The intrusion is intimately veined by a
quartz stockwork in which
molybdenite
is the most important economic mineral. The metallic minerals common to most of the
quartz veins include molybdenite,
pyrite, galena,
sphalerite, chalcopyrite,
pyrrhotite, tetrahedrite,
cosalite and aikinite. The
quartz vein containing the nuffieldite differs from the others in
that it lacks chalcopyrite,
pyrrhotite and tetrahedrite.
The vein is 1 inch wide and contains small pyrite cubes and
molybdenite flakes along the edges; the sulphosalt crystals are in
1-3 mm diameter vugs. Only two of the vugs were found to contain nuffieldite. The other vugs contained
cosalite, aikinite and a new
sulphosalt mineral. The only metallic mineral observed in contact with nuffieldite is
aikinite
(CM 9.439-452).
At the Maleevskoe deposit, Altai Krai, Russia, nuffieldite is reported from a
pyrite-rich massive sulphide deposit, as microscopic platy crystals
and as aggregrates of grains up to 0.6 mm within a
copper-zinc rich zone. Associated
minerals include
hessite, tetradymite,
electrum, aikinite,
lindströmite, hammarite,
cosalite, kobellite,
galenobismutite, gudmundite,
berthierite and nisbite
(CM 32.359-364).
At the Alaska Mine, Poughkeepsie Gulch, San Juan county, Colorado, USA, nuffieldite is associated with
neyite,
galena, tetrahedrite,
chalcopyrite and sphalerite
(HOM).
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