Joëlbruggerite

joelbruggerite

mimetite

dugganite

kuksite

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Formula: Pb3Zn3(Sb5+,Te6+)As2O13(OH,O)
Arsenate, dugganite group, antimony- and tellurium- bearing mineral
Crystal system: Trigonal
Specific gravity: 6.73 calculated for the empirical formula
Hardness: 3
Streak: White
Colour: Light purple, bluish purple, greyish purple
Luminescence: Not fluorescent under UV
Environments

Hydrothermal environments

Localities

At the type locality, the Black Pine Mine, Philipsburg Mining District, Granite County, Montana, USA, Joëlbruggerite is usually found perched on mimetite; other species that may be present include malachite, azurite, pseudomalachite, chalcocite, beudantite-corkite, duftite, and the two joëlbruggerite-related species dugganite and kuksite, in milky quartz veins. The Black Pine mine is also the type locality for philipsburgite and is noted for its exceptional crystals of veszelyite.
Joëlbruggerite crystallised from solutions rich in Pb, Zn, Sb, As and Te derived from the breakdown of the primary ore body. The primary ore is hosted by veins of quartz with a comb texture, which is commonly vuggy, with the principal primary minerals being silver-bearing tetrahedrite, hübnerite and pyrite. Galena, sphalerite, chalcopyrite and native gold, silver and copper are minor constituents within the veins. Tellurium is probably included in trace amounts within the tetrahedrite or possibly as gold-silver tellurides.
The formation of joëlbruggerite is likely to have occurred in a highly oxidising environment, in water near equilibrium with atmospheric oxygen, similar to other secondary tellurium minerals such as xocolatlite
Joëlbruggerite occurs as barrel-shaped or stout hexagonal prismatic crystals up to about 50 µm across. Crystals occur in various shades of purple and can be colour-zoned, with light purple and greyish purple most prominent. Joëlbruggerite crystals are transparent, with a white streak and adamantine lustre (AM 94.7.1012-1017).

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