南秦岭大型钡成矿带中硫钒铜矿的特征及成因意义

MINERALOGICAL CHARACTERISTICS AND GENETIC SIGNIFICANCE OF SULVANITE FROM THE LARGE BARIUM METALLOGENIC BELT IN SOUTHERN QINLING MOUNTAINS,CHINA

在南秦岭下寒武统硅岩建造中的毒重石-重晶石矿床中,产出大量硫钒铜矿。硫钒铜矿呈正方形,长方形及不规则状,粒度大小变化较大,一般为0.01mm～1mm,最大可达7mm。反光显微镜下为淡柠檬黄色,显微硬度134.5kg/mm2～139.8kg/mm2,相当于摩氏硬度3.46～3.50。主要化学成分为:Cu47.18～52.02(平均50.44),V6.50～14.32(平均11.95),Sn0.00～12.85(平均2.15),S31.77～34.34(平均33.29),As0.00～5.12(平均0.86),Fe0.00～3.27(平均0.77),部分样品含有极少量的Fe,Ni,Co,Sb,Se,Te,In。相应的平均化学分子式为Cu3.04(V0.90,Sn0.07,Fe0.05,As0.04,Sb0.01)1.07(S3.98,Se0.02)4.00,简化式为:Cu3(V,Sn,As,Fe)S4。矿物为等轴晶系,晶胞参数值a=0.5392nm。成矿带中硫钒铜矿的形成与钒的富集,与有机质演化受热和生物降解作用有密切联系。

Sulvanite occurred in the Lower Cambrian silicalite and slate in the large barium metallogenic belt of southern Qinling Mountains. Samples were collected from witherite, barite, and barytocalcite ores. Sulvanite was disseminated in the ores with square, rectangular or irregular shape and with grain sizes of 0.01 mm～l mm. The mineral was light lemon yellow in color, metallic in luster and brashy,134.5 kg/mm^2 ～139.8 kg/mm^2 （for 50 g load） in microhardness and Moh＇s=3.46～3.50. Electron microprobe analyses of 12 points on sulvanite gave the results as follows（%）.Cu 47.18～52.02 （50.44 on average）, V 6.50～14.32 （11.95 on average）,Sn 0.00～12.85 （2. 15 on average）, S 31.77～34.34 （33.29 on average）, As 0.00～5.12 （0.86 on average）, Fe 0.00～3.27 （0.77 on average） ,corresponding to the formula Cu3.04 （V0.90 ,Sn0.07 ,Fe0.05, As0. 04, Sb0. 01 ） 1.07 （S3.98, Se0.02 ） 4.00, and to a simplified formula Cu3 （V, Sn, As, Fe） S4. The mineral was of cubic system,a=0. 539 2 nm. It was considered that the enrichment of sulvanite and vanadium in the belt would be favored by both heated organic matters and biodegradation.