Tags: Chemical Substance, Mineral.
Geigerite is a mineral a complex hydrous manganese arsenate with formula: Mn5(AsO3OH)2(AsO4)2·10H2O. It forms triclinic pinacoidal vitreous colorless red to brown crystals. It has a Mohs hardness of 3 and a specific gravity of 3.05.It was discovered in Grischun Switzerland in 1989. It was namedin honor of Thomas Geiger (1886–1976) Wiesendangen Switzerland who studied the Falotta manganese ores.