Jamesite Locality: Tsumeb Mine (Tsumcorp Mine), Tsumeb , Otjikoto (Oshikoto) Region, Namibia ( Locality at mindat.org ) Size: 4.3 x 3.5 x 2.8 cm. A specimen rich with small red microcrystals of the rare arsenate Jamesite, from the type locality, in veins mixed with duftite and on contrasting white dolomite. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Jamesite
Jamesite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Pb₂ZnFe³⁺₂(Fe³⁺,Zn)₄(AsO₄)₄(OH)₈(OH,O)₂.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 3; specific gravity 5.084; Pale brown streak; Subadamantine luster; optically biaxial.
IMA symbol Jms, IMA status: approved, named in 1978.
Found as a secondary mineral in oxidized lead ore in a dolostone-hosted hydrothermal polymetallic ore deposit.
It is found associated with Duftite, tsumcorite, goethite.
The mineral was named to honor Christopher James, one of the first mining engineers at the Tsumeb mine, Namibia.