Junoite

junoite

heyrovskyite

krupkaite

proudite

Images

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

Hydrothermal 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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