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Formula: Ag5Cu3S4
Sulphide of silver and copper
Crystal System: Orthorhombic
Specific gravity: 6.61 measured, 6.57 calculated
Hardness: 1½ to 2½
Streak: Dark steel-grey
Colour: Steel-grey, tarnishes to dark grey to black
Environments
Mckinstryite is of hydrothermal or supergene origin,
probably formed below 94.4oC, the upper stability
limit for mckinstryite
(HOM).
Localities
At the Sedmochislenitsi mine, Balkan Mts, Vratsa Province, Bulgaria, mckinstryite is associated with
bornite, chalcocite,
chalcopyrite, djurleite,
digenite, tennantite,
stromeyerite, wittichenite,
bismuth, rammelsbergite,
balkanite, mercurian
silver, cinnabar,
pyrite, calcite,
baryte and aragonite
(HOM).
At the Echo Bay mine, Port Radium District, Great Bear Lake, North Slave Region, Northwest Territories, Canada,
mckinstryite occurs as a late-stage, primary sulphide
in the uranium = cobalt -
nickel - silver -
bismuth deposit, accompanying
nickeline, rammelsbergite,
chalcopyrite, bornite,
covellite and early dolomite
(EG 66.342-347).
At the type locality, the Foster mine, Coleman Township, Cobalt area, Cobalt-Gowganda region, Timiskaming District,
Ontario, Canada, mckinstryite occurs as masses of intergrown crystals 0.2 to 3 mm in diameter in a
silver - cobalt -
nickel - copper deposit. Associated
minerals include chalcopyrite,
stromeyerite, calcite,
actinolite, silver and
arsenopyrite
(Mindat).
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