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Formula: Ag3CuS2
Crystal System: Tetragonal
Specific gravity: 6.82 -to 6.85 measured, 6.827 calculated
Hardness: 2 to 2½
Streak: Black
Colour: Grey or dark grey, tarnishes lustrous dark grey, locally to a
chalcopyrite-like iridescence
Common impurities: Fe
Environments
Jalpaite is formed under low-temperature (below 117◦C) hydrothermal conditions. Associated minerals include
acanthite, mckinstryite,
galena, sphalerite,
pyrite, chalcopyrite,
stromeyerite, polybasite,
pearceite,
tetrahedrite–tennantite
and silver
(HOM).
Localities
At Charcas, Charcas Municipality, San Luis Potosí, Mexico,
the primary minerals are
sphalerite, galena,
chalcopyrite, bornite,
tetrahedrite,
arsenopyrite, pyrite and
silver minerals such as jalpaite,
diaphorite and acanthite. In
the host rock, as metamorphic or alteration minerals, danburite,
datolite, hedenbergite,
epidote, chlorite,
andradite, actinolite
and wollastonite have been reported.
Quartz, calcite and
danburite crystallised during the entire life of the systems, throughout
the intrusive emplacement, metamorphism, and mineralising events. With depth, both
sphalerite and galena decrease
while chalcopyrite increases.
Secondary sulphides formed include
bornite, covellite,
digenite and chalcocite.
Native silver, native gold,
hematite and goethite were
deposited after the sulphides
(Minrec 55.6.727-728).
Jalpaite occurs as fine microscopic inclusions in chalcopyrite
(Minrec 55.6.757)
The type Locality is the Leonera Mine, Jalpa, Jalpa Municipality, Zacatecas, Mexico.
Jalpaite from Jalpa - Image
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