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Hübnerite is a mineral consisting of manganese tungstate (chemical formula: MnWO4). It is the manganese endmember of the manganese - iron wolframite solid solution series. It forms reddish brown to black monoclinic prismatic submetallic crystals. The crystals are typically flattened and occur with fine striations. It has a high specific gravity of 7.15 and a Mohs hardness of 4.5. It is transparent to translucent with perfect cleavage. Typical occurrence is in association with high-temperature hydrothermal vein deposits and altered granites with greisen, granite pegmatites and in alluvial deposits. (source: Wikipedia) Photo by Michael Marcotte (showing very small silver crystals of Hübnerite on bed of quartz crystals) Photo by iRocks at Arkenstone.com Return to List Back to Michael's Hobbies page Back to Michael Marcotte's HomePage