Metarauchite
A dehydrated nickel uranyl arsenate of the autunite group, found at Jáchymov and Schneeberg.
Intro adapted from Wikipedia (CC BY-SA).
Metarauchite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Ni(UO₂)₂(AsO₄)₂·8H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Autunite structural group.
Key properties: Mohs hardness 2; specific gravity 3.81; Light green to pale yellow streak; Vitreous, pearly on (011) luster; optically biaxial.
IMA symbol Mrau, IMA status: approved, named in 2008.
Found as a secondary mineral in strongly oxidized polymetallic vein material.
It is found associated with Metazeunierite, erythrite, gypsum (Jáchymov); Ni-bearing metanováčekite, metazeunerite, pharmacosiderite (Schneeberg).
The mineral was named to honor Czech mineral collector Luděk Rauch (1951-1983) who died prospecting in the Jáchymov mines.