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Formula: Cu2Pb3Bi8(S,Se)16
Sulphosalt, copper-, lead-,
bismuth- and selenium-
bearing mineral
Crystal system: Monoclinic
Specific gravity: 6.77 calculated
Hardness: 3½ to 4
Colour: Grey
Common impurities: Ag
Environments
Localities
The type locality, the Juno Mine, Tennant Creek, Barkly Region, Northern Territory, Australia, has been mined for
gold, bismuth,
copper, silver and
selenium. The deposit is made up of smaller ore bodies which are usually
zoned with an outer shell of dolomite, an inner shell of
magnetite-dolomite rock, and
a core of massive magnetite containing the ore minerals and some
silicates
(AM 60.548-558).
Minerals associated with junoite include gold,
selenium-bearing
heyrovskýite, krupkaite,
proudite, chalcopyrite and
magnetite
(HOM).
Junoite from the Juno Mine - Image
At the Kidd Mine, Kidd Township, Timmins, Cochrane District, Ontario, Canada, junoite is the most abundant
bismuth-bearing mineral, and it occurs in association with
magnetite, chalcopyrite,
proudite and members of the
bismuthinite-aikinite
series. Selenium-bearing
heyrovskýite and
emplectite are other bismuth
sulphosalts that have been identified from the mine. Members of the Juno
aikinite-bismuthinite
series include krupkaite,
pekoite and gladite.
Junoite has been found in only one specimen from the Kidd Creek mine, from a bore-hole. The main opaque
mineral in this specimen is chalcopyrite, whereas
sphalerite is less abundant and junoite,
cobaltite, kësterite and
mawsonite are minor constituents.
Cobaltite occurs as small grains included in
chalcopyrite, less commonly in
sphalerite, and in some cases associated with and included in
junoite. Small blebs of kësterite are present as inclusions in
chalcopyrite, and rarely in
sphalerite. Mawsonite is
present as a few blebs in chalcopyrite, and in one case, it was
observed as a very fine partial rim on kësterite.
Junoite generally forms discrete grains up to about 0.5 mm long and 0.3 mm wide that are isolated in
gangue or included in
chalcopyrite. Less commonly, junoite lamellae about 20
microns wide and 150 microns long occur in chalcopyrite and, rarely,
in sphalerite. Small blebs of junoite, although not abundant,
are present as inclusions in chalcopyrite and
sphalerite
(CM 18.3.353-360).
At the Kockbulak mine, Ohangaron District, Tashkent Region, Uzbekistan, juoite is of hydrothermal origin,
and occurs associated with pekoite,
tetradymite, aikinite,
gladite and cassiterite
(HOM).
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