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Formula: Bi3O(AsO4)2(OH)
Anhydrous arsenate containing hydroxyl,
preisingerite group,
bismuth-bearing mineral, forms series with
petitjeanite and
schumacherite
Crystal System: Triclinic
Specific gravity: about 6 measured, 7.24 calculated
Hardness: 3 to 4
Streak: White
Colour: White to grey
Environments:
Preisingerite is a rare secondary mineral in the oxidised zone of
some arsenic-bearing hydrothermal mineral deposits.
At the type locality, the San Francisco de los Andes mine, San Juan, Argentina, preisingerite is found in the weathering zone
associated with
rooseveltite, mixite,
beudantite and
bismutite.
(HOM)
This mine is a breccia pipe deposit, related to
granodiorite plutons, with tourmaline,
quartz and other minerals. The most
abundant primary ore minerals are pyrite,
arsenopyrite, bismuthinite,
chalcopyrite, digenite and
tetrahedrite. The deposit once
contained a substantial weathering zone with many arsenate minerals which originated from the decomposition of
arsenopyrite, scorodite,
beudantite, olivenite,
conichalcite, clinoclase,
rooseveltite and preisingerite.
(AM67.833-840)
At Cerro Negro de la Aguadita, which is
a trench in the weathering zone of a deposit of the same type as San Francisco de los Andes,
rooseveltite, preisingerite and
mixite were found. In both deposits preisingerite usually occurs together with
rooseveltite; these are the most abundant
bismuth minerals in the weathering zone, while bismutite and
mixite are infrequent. Preisingerite frequently forms
pseudomorphs after bismuthinite,
and it is occasionally found as masses
impregnated by small quantities of beudantite or
bismutite
(AM67.833-840).
At the Clara mine, Baden-Württemberg, Germany, preisingerite is associated with
bismutostibiconite,
atelestite and beyerite
(HOM).
At Schneeberg, Saxony, Germany, preisingerite has been found on a specimen of
pucherite
(AM67.833-840).
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