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Formula: Pb2(Se6+O4)(SO4)
Selenate
Crystal System: Orthorhombic
Specific gravity: 6.55 calculated
Hardness: 3 to 3½
Streak: White
Colour: Colourless
Electrical properties: Pyroelectric
Environments
Sedimentary environments
Hydrothermal environments
Olsacherite is a rare secondary mineral in the oxidised
zone of selenium-bearing hydrothermal mineral deposits, where it occurs as
an alteration product of penroseite
(HOM, Mindat).
Localities
At El Dragón mine, Porco Municipality, Antonio Quijarro Province, Potosí, Bolivia, olsacherite is associated
with chalcomenite, ahlfeldite,
lepidocrocite and goethite
(HOM).
At the type locality, the Virgen de Surumi mine, Pakajake Canyon, Chayanta Province, Potosí, Bolivia, the deposit is
a vein enclosed in sandstone. In this deposit the
primary minerals are
penroseite, clausthalite,
naumannite, tiemannite,
pyrite, siderite,
baryte, hematite and
calcite; the
secondary minerals are
cerussite, anglesite,
wulfenite, limonite,
chalcomenite, ahlfeldite and
native selenium.
Olsacherite is an alteration product of penroseite and occurs very
sparingly as well formed crystals coating the walls of small cracks or cavities
(AM 54.1519-1527).
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