我国产出的鳞镁铬矿-鳞镁铁矿系列的过渡矿物——铬鳞镁铁矿

CHROM-PYROAURITE, Mg_6(Fe^(3+),Cr)_2CO_3(OH)_(16)·4H_2O,A NEW VARIETY ON THE PYROAURITE-STICHITITE JOIN

Chrom-pyroaurite, associated with serpentine, chromite, magnetite, ehaleopyrite,pyrite and etc., is found in serpentinite in Southwestern China. Its coiour is violet in aggregate, but colorless or pale pink in thin fragments. The mineral is transparent with glassy luster. Specific gravity 2.12±0.01 (determined by s.g. bottle).Hardness 1--1.5. It occurs in massive aggregate and is of apparent greasy feel. Under microscope it has scaly and fibrous appearance. Pleochroism is not clear with N.--colorless, No--pale pink. Uniaxial negative. No = 1.5560, N, = 1.5450, No -- N4=0.011. Apparent endothermic peaks are noticed at 270° and 460℃ respectively.Chemical composition is gaven as: MgO 36.74, 35.62; FeO 0.1, 0.15; MuO 0.06, 0.01;Fe2O3 13.54, 12.79; Cr2O3 6.94, 7.49; Al2O3 2.21, 1.74; CO2 6.45, 7.78; H2O^+ 32.33, 32.30;H2O^- 2.38, 1.78; total 100.75, 100.56. The mineral belongs to trigonal system, α0=6.165A, c0= 46.760A, c0/α0 = 7.585. Cell dimension V= 1537A^3, Z = 3. Strongest Xray pattern lines are 10.48(8), 8.56(5), 7.8(10), 5.12(4), 3.89(10), 2.60(5), 1.99(6).The mineral is named after its eomposition.

Chrom-pyroaurite, associated with serpentine, chromite, magnetite, chalcopyrite,pyrite and etc., is found in serpentinite in Southwestern China. Its colour is violet inaggregate, but colorless or pale pink in thin fragments. The mineral is transparentwith glassy luster. Specific gravity 2.12 ± 0.01 (determined by s.g. bottle). Hardness1--1.5. It occurs in massive aggregate and is of apparent greasy feel. Undermicroscope it has scaly and fibrous appearance. Pleochroism is not clear with N_o——colorless, N_e——pale pink. Uniaxial negative. N_o = 1.5560, N_e = 1.5450, N_o - N_e =0.011. Apparent endothermic peaks are noticed at 270° and 460℃ respectively.Chemical composition is gaven as: MgO 36.74, 35.62; FeO 0.1, 0.15; MnO 0.06, 0.01;Fe_2O_3 13.54, 12.79; Cr_2O_3 6.94, 7.49; Al_2O_3 2.21, 1.74; CO_2 6.45, 7.78; H_2O^+ 32.33, 32.30;H_2O^- 2.38, 1.78; total 100.75, 100.56. The mineral belongs to trigonal system. α_0 =6.165 A, c_0 = 46.760 A, c_0/α_0 = 7.585. Cell dimension V = 1537 A^3, Z = 3. Strongest X-ray pattern lines are 10.48(8), 8.56(5), 7.8(10), 5.12(4), 3.89(10), 2.60(5), 1.99(6).The mineral is named after its composition.