Yanomamite, InAsO4.2H2O, a new indium mineral from topaz-bearing greisen in the Goiás Tin Province, Brazil

Yanomamite occurs as green to yellow-green idiomorphic crystals in aggregates associated with scorodite in quartz-topaz greisen in the tin deposit of Mangabeira, Goias State, Brazil. Yanomamite crystals are always coated by a thin film ofIn-rich scorodite. Microprobe analyses give (wt. 'Yo): In203 45.8(3), Fe203 1.1(2), Ab03 0.21(2), AS205 40.1 (2), H20 12.78 by difference, with the structural formula (Ino.94FeO.04A10.01)As04 . 2.02 H20. Yanomamite is isotypic with scorodite, and belongs to the variscite series. The mineral is orthorhombic,