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Formula: (Cu4☐2)Cu6Te4S13
Sulphosalt, goldfieldite subgroup of the
tetrahedrite group,
tellurium-bearing mineral
Crystal System: Isometric
Specific gravity: 4.95 measured, 4.935 calculated
Hardness: 3 to 3½
Streak: Black
Colour: Dark lead-grey
Luminescence: Not fluorescent under UV
Magnetism: Not magnetic
Common impurities: Ag,Fe,Zn,Bi
Environments
Volcanic igneous environments
Hydrothermal environments
Goldfieldite occurs in epithermal gold-bearing veins, and less commonly
in porphyry copper and
volcanogenic massive sulphide deposits. Associated minerals include
marcasite, famatinite,
tennantite, hessite,
petzite, sylvanite,
altaite, chalcostibite,
emplectite, gold,
kuramite, bismuthinite,
pyrite and sphalerite
(HOM ).
Localities
At the Pittsburg-Liberty Mine, New York Hill, Masonic Mining District, Bodie Hills, Mono county, California, USA,
bodieite has been found on several specimens collected from the lower dump
of the mine. It occurs in vugs in quartz with embedded crystals of
goldfieldite, bismuthinite and
famatinite–luzonite. Other
closely associated minerals include baryte,
mixite and richelsdorfite
(CM 56.763-772).
Goldfieldite from the Pittsburg-Liberty
Mine - Image
The type locality is the Mohawk Mine, Goldfield, Goldfield Mining District, Esmeralda County, Nevada, USA.
Goldfieldite from the Mohawk Mine -
Image
At the Tintic Mining District, Juab County, Utah, USA, goldfieldite is known to occur at the Centennial
Eureka, Trixie, and North Star mines. Single tetrahedral crystals around 0.5 mm in size have been found at the
Trixie mine; octahedral crystals to 0.1 mm have been found at the North Star mine; crude, corroded crystals to 1 mm
have been found in the Centennial Eureka mine — all of these occurring on
quartz. At the North Star mine, goldfieldite is the most common
telluride; several centimetre-sized areas and millimetre-sized blebs of
formless masses of black metallic goldfieldite have been found in a matrix of grainy
quartz. Although small, the sharp crystals that have been found in the
district represent very good examples of the species
(MinRec 55.2.203-204).
Goldfieldite from Tintic - Image
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