Olsacherite

olsacherite

penroseite

ahlfeldite

chalcomenite

Images

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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