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Formula: Bi4Te2S
Sulphotelluride, tetradymite group,
tellurium-bearing mineral
Crystal System: Trigonal
Specific gravity: 8.30 measured, 8.44 calculated
Hardness: 2
Streak: Grey
Colour: Silver-white, tarnishing to lead-grey
Luminescence: Not fluorescent under UV
Environments
Pegmatites
Metamorphic environments
Joséite-B is associated with bismuth,
gold, joséite-A,
bismuthinite, ikunolite,
hedleyite, pyrrhotite,
arsenopyrite and
molybdenite
(HOM).
Localities
There are two co-type localities, the São José mine (Tesoureiro mine), Camargos district, Mariana, Minas Gerais,
Brazil, and Glacier Gulch, Smithers, Omineca Mining Division, British Columbia, Canada.
At El Quemado deposit, El Quemado mining district, La Poma Department, Salta Province, Argentina, an assemblage of
bismuth-rich, tellurium-bearing
minerals in El Quemado pegmatite represents late-stage
mineralisation in the spodumene-subtype, rare-element class
granitic
pegmatite. The minerals occur in an association dominated by
fine-grained muscovite and quartz,
with accessory uranium-rich
fluornatromicrolite,
zircon, bismuth,
bismuthinite, emplectite,
hodrušite, and the sulphotellurides
joséite-A, joséite-B,
tetradymite and ingodite.
Early bismuth is replaced by abundant
bismuthinite, which also contains intergrowths of
emplectite. A single euhedral crystal of
hodrušite with lead-bearing tips has
been found. Joséite-A forms an intergrowth with
ingodite, enclosed in
emplectite. Joséite-B is intergrown with
joséite-A and with
bismuthinite in emplectite.
Tetradymite is included in
emplectite and bismuthinite.
Ingodite is usually enclosed in
bismuthinite as very small grains. Late-stage or
supergene alteration of this association generated fairly
abundant bismutite and rare
bismite.
Experimental data indicate that the equilibrium association of bismuth,
bismuthinite, emplectite
and hodrušite, typical of hydrothermal ore deposits but uncommon in
granitic
pegmatites, is restricted to relatively low temperatures
and a pressure of 2 to 3 kbar
(CM 50.6.1489-1498).
The São Sebastião deposit, São José da Varginha, Minas Gerais, Brazil, is a recently (in 2015) discovered
gold deposit in the Pitangui
greenstone belt. Part of its hydrothermal system is characterised
by chaotically distributed tourmaline that is concentrated in patchy
domains, or pockets. Pyrrhotite and late
chalcopyrite occur in the
tourmaline-rich pockets. Bismuth,
bismuth–gold intermetallic aggregates,
and bismuth-telluride minerals
locally fill microfractures that are superimposed on preexisting,
chalcopyrite-bearing microfractures in the
tourmaline-rich pockets.
Hedleyite and ehrigite? make up
composite aggregates with joséite-B. The gold –
bismuth – tellurium mineral
assemblages indicate precipitation below about 270°C
(CM 53.6.1061–1072).
The Pirunkoukku gold occurrence, Säkkärämäki, Kanalanmäki area, Pihtipudas, Central Finland, Finland, is localised
within intensely altered felsic to intermediate volcanic rocks in the
contact zone of a granite massif. A
chalcopyrite association and an
arsenopyrite association represent the two major mineral assemblages.
The chalcopyrite association is dominantly composed of
chalcopyrite, pyrrhotite,
magnetite and marcasite, as
well as minor and rare minerals including silver-bearing
chalcopyrite, cubanite,
native bismuth, joseite-B,
matildite, schapbachite,
hessite, molybdenite,
arsenopyrite, sphalerite,
electrum and gold-bearing
silver. Due to
the presence of cubanite, a formation temperature of 250 to 300°C is
estimated for the chalcopyrite association.
Arsenopyrite and lollingite
are the dominant minerals in the arsenopyrite association. Minor and
rare minerals present in this association include chalcopyrite,
electrum, maldonite,
aurostibite, bismuth
tellurides and native bismuth.
(EJM 27.5.639–649).
At Stanos, Aristotelis, Chalkidiki, Central Macedonia, Greece, arsenic -
copper - gold -
bismuth mineralisation is hosted by a shear zone within Silurian (443.7
to 416.0 million years ago) orthogneiss. Shearing was accompanied by
iron-potassic alteration of the gneiss including
biotite, muscovite,
chlorite, apatite,
zircon, quartz and minor
rare-earth element phosphates.
Two stages of hydrothermal mineralisation occurred during shearing. An initial introduction of the iron sulphides
pyrite, arsenopyrite and
pyrrhotite was followed by a
copper-bearing stage that is associated with the formation of
chalcopyrite, minor sulphides
galena, sphalerite and
molybdenite, and bismuth -
copper - lead -
gold - silver -
tellurium minerals.
The second stage consists mainly of the bismuth sulphosalts
bismuthinite derivatives,
lillianite homologues and
matildite, the native elements
bismuth and electrum, and the
bismuth chalcogenides including
joséite-A, joséite-B and
ikunolite. The
bismuthinite derivatives are mainly
bismuthinite (including cuprian varieties),
gladite-krupkaite,
paarite, salzburgite and an
unnamed CuPbBi7S12 phase.
The assemblages in paragenetic order are:
molybdenite + cosalite +
native bismuth +
galenobismutite
→
gustavite/lillianite +
native gold + native bismuth +
bismuth sulphotellurides
→
bismuthinite-aikinite solid
solution series
→
matildite + native bismuth +
galena
→
chalcopyrite + bornite
(CM 51.1.119-142).
At the Viceroy Mine, Goromonzi District, Mashonaland East, Zimbabwe, gold
mineralisation is hosted in veins in steep shear zones that transect
metabasalt of Archaean age (4,031 to 2,500 million years ago). The
gold mineralisation is generally made up of banded or massive
quartz carrying abundant coarse
arsenopyrite. However, most striking is a distinct suite of
gold - bismuth -
tellurium - sulphur minerals,
namely joseite-A, joseite-B,
hedleyite, ikunolite,
bismuthinite, native bismuth,
native gold, maldonite,
jonassonite and some unnamed minerals. It appears that this assemblage
formed at reduced conditions and depositional temperatures of up to 342oC
(MM 72.4.953–970).
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