Pyroxmangite: Gemstone Information
Pyroxmangite is Mn2SiO3 and forms frequently twinned translucent red tabular crystals of the triclinic system with a perfect cleavage in one direction, hardness 5.5–6 and SG 3.61–3.80. The RI for the alpha, beta and gamma rays is 1.728–1.748, 1.730–1.742, 1.746–1.758, biaxial positive with birefringence 0.016–0.020. Pyroxmangite occurs in regionally metamorphosed manganese ore deposits and in manganiferous rocks. Fine crystals come from the Taguchi and other mines, Shidara, Aichi prefecture,Japan, and large crystals from Broken Hill, New South Wales, Australia.