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A group of mantle minerals including about 70-80 subtypes of minerals are discovered from a podiform chromitite in Tibet,China.Recovered minerals include diamond,coesite,moissanite,wustite,Fe-silides and a new mineral,luobusaite.All of these minerals were hand-picked from heavy-mineral separates of the podiform chromitite in the mantle peridotite of an ophiolite.The grains of luobusaite are as host mineral with inclusions of native silicon or as an intergrowth with native silicon and Fe-Si phase.Luobusaite occurs as irregular grains,with 0.1-0.2 mm in size,consisting of very fine-grained aggregates.The mineral is steel-grey in color,metallic luster,and opaque.The empirical formula(based on 2 for Si)is Fe0.83Si2,according to the chemical compositions of luobusaite.X-ray powder-diffraction data:orthorhombic system,space group Cmca,a = 9.874(14)?,b = 7.784(5)?,c= 7.829(7)?,Z=16.
A group of mantle minerals including about 70-80 subtypes of minerals are discovered from a podiform chromitite in Tibet, China. Recovered minerals include diamond, coesite, moissanite, wustite, Fe-silides and a new mineral, luobusaite. All of these minerals were hand-picked from heavy-mineral separates of the podiform chromitite in the mantle peridotite of an ophiolite. The grains of luobusaite are host minerals with inclusions of native silicon or as an intergrowth with native silicon and Fe-Si phase. Luobusaite as as irregular grains, with 0.1-0.2 mm in size, consisting of very fine-grained aggregates. The mineral is steel-gray in color, metallic luster, and opaque. The empirical formula (based on 2 for Si) is Fe0.83Si2, according to the chemical compositions of luobusaite. X-ray powder-diffraction data: orthorhombic system, space group Cmca, a = 9.874 (14) ?, b = 7.784 (5) ?, c = 7.829 (7) ?, Z = 16.