Olsacherite Locality: El Dragón mine, Antonio Quijarro Province , Potosí Department , Bolivia ( Locality at mindat.org ) Picture width 2 mm. Collection and photograph Christian Rewitzer — Photo: Christian Rewitzer · CC BY-SA 3.0
Olsacherite
Olsacherite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Pb₂(Se⁶⁺O₄)(SO₄).
It crystallizes in the orthorhombic crystal system (space group P22_12). It is a member of the Baryte structural group.
Key properties: Mohs hardness 3–3.5; specific gravity 6.55; White streak; Vitreous, dull if coated luster; optically biaxial.
IMA symbol Ols, IMA status: approved, named in 1969.
A rare secondary mineral found in the oxidized zone of selenium-bearing hydrothermal mineral deposits.
It is found associated with Penroseite (Pacajake mine, Bolivia); chalcomenite, ahlfeldite, lepidocrocite, goethite (El Dragón mine, Bolivia).
The mineral was named to honor Juan Augusto Olsacher (1903–1964), Professor of Mineralogy, Córdoba University, Córdoba, Argentina, who studied Argentinian selenium-bearing minerals.