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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
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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