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Formula: Ag3AsS3
Valence: Ag1+3As3+S2-3
Sulpharsenite,
proustite group, monoclinic
paramorph
of proustite, which is trigonal; the xanthoconite →
proustite transition occurs at 180-202oC (Mindat).
Crystal System: Monoclinic
Specific gravity: 5.54 measured, 5.53 calculated
Hardness: 2 to 3
Streak: Orange-yellow
Colour: Red-orange, yellow-orange, red-brown, brown
Environments
Xanthoconite typically is associated with other silver sulphosalts in hydrothermal veins.
Associated minerals include
proustite, pyrargyrite,
acanthite, arsenic and
calcite
(HOM, Mindat).
Localities
At Grande Haldes, Sankt Ludwig vein, Neuenberg, Sainte-Marie-aux-Mines, Colmar-Ribeauvillé, Haut-Rhin, Grand Est, France,
xanthoconite has been found
(Mindat photo).
Xanthoconite from Grange Haldes - Image
The type locality is the Himmelsfürst mine, Brand-Erbisdorf, Mittelsachsen, Saxony, Germany.
Xanthoconite from the Himmelsfürst Mine -
Image
At the Imiter mine, Tinghir Cercle, Tinghir Province, Drâa-Tafilalet Region, Morocco, xanthoconite is chiefly confined to the
quartz veins of the later-stage silver assemblages, where
silver it is associated with
polybasite-pearceite,
galena, and less commonly with arsenopyrite.
It is also found in small amounts in cavities in black shale with
proustite and titanite
(Min Rec 42.2.133-135).
Xanthoconite from the Imiter Mine -
Image
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