Mandarinoite 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
Mandarinoite
Mandarinoite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Fe³⁺₂(Se⁴⁺O₃)₃·6H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Mandarinoite structural group.
Key properties: Mohs hardness 2.5; specific gravity 2.93; Very pale green streak; Vitreous to slightly greasy luster; optically biaxial.
IMA symbol Mda, IMA status: approved, named in 1977.
Probably formed by the simultaneous oxidation of penroseite and pyrite in a selenium-rich ore deposit (Pacajake mine, Bolivia).
It is found associated with Penroseite, siderite, goethite, quartz (Pacajake mine, Bolivia); chalcomenite, kruťaite (El Dragón mine, Bolivia); chlorargyrite (De Lamar mine, Idaho, USA).
The mineral was named to honor Dr. Joseph Anthony Mandarino (1929–), American–Canadian mineralogist, Emeritus Curator of Mineralogy, Royal Ontario Museum, Toronto, Canada.