【摘要】 甘肃省临洮县马衔山存在软玉矿脉。对绿色、黄绿色、黄褐色的马衔山软玉样品进行了常规宝石学、红外光谱、电子探针、扫描电镜测试及偏光显微镜观察。结果表明,样品的点测折射率为1.61,密度为2.917～2.941 g/cm³（不含风化层）,摩式硬度为6～6.5,具油脂光泽,韧度很高,主要组成矿物为透闪石（w（SiO₂）=57.06%～58.44%、w（MgO）=23.42%～24.13%、w（CaO）=12.24%～13.04%）,次要矿物为透辉石、绿帘石、磷灰石、榍石、斜黝帘石等,主要为显微纤维变晶结构或毛毡状变晶结构,各项特征均符合软玉的国家鉴定标准,同时推测样品的绿色深浅与Fe含量有关。此外,样品常存在白色风化层,内有沿裂隙分布的褐色树枝状物质（俗称"蚂蚁脚"或"藻丝纹"）,在白色风化层和玉质部分间常出现褐色过渡层。更多还原

【Abstract】 There are veins of nephrite in the Maxianshan area, Lintao County, Gansu Province. In this paper, the green,yellowish green and brown colored nephrite samples were investigated using the conventional gemological method,infrared spectroscopy, electron probe, scanning electron microscope, and polarizing light microscopy. The results show that the nephrite samples have the spotty measured refractive indexes of 1.61, densities of 2.917-2.941 g/cm³（ not including the weathered layer）, Mohs hardnesses of 6-6.5, with greasy luster and high toughness. The nephrite samples contain essential mineral of tremolite（w（SiO₂）=57.06%-58.44%, w（MgO）=23.42%-24.13%, w（CaO）=12.24%-13.04%）, and auxiliary minerals of diopside, epidote, apatite, sphene, and clinozoisite, with major micro-fiber crystalloblastic or felt-like crystalloblastic textures. All these characteristics are consistent with those of the China national standard of nephrite. It is believed that the green color intensities of samples could be related to the Fe contents. In addition, there are white weathered layers with brown dendritic substances（with nickname of "ant feet" or "algae stripes"）distributed along fissures in nephrite, and brown transition layers between the white weathered layer and nephrite body.更多还原