祁连绿宝石及其成矿作用初步研究

Primary Study on the Qilian Green Gem and its Mineralization

在青海省祁连县玉石沟发现了一种葱绿色的矿物晶体，其大小可以切磨戒面，笔者将它命名为‘祁连绿宝石”，实际上其矿物学名称是符山石。电子探针分析结果表明，这种符山石与一般矽卡岩型符山石在化学组分上略有区别。这种宝石矿脉产于超镁铁岩体边缘的辉长岩捕虏体带，其直接围岩为钙铝榴石岩（祁连翠玉）。它是低温热液沿钙铝榴石岩裂隙交代蚀变而形成的，成矿时间在超镁铁岩多期蛇纹石化过程的晚期。

A kind of fresh guen mineral crystal whose size is big enough to cut a ring gem has been found in Yushigou of Qilian county in Qinghai. The crystal is named as Qilian Green Gem by the author, and its mineralogical name really is vesuvianite. It is showed that the chemical composition of the gem is a little different from that of a common skam vesuvianite by the results of electron probing analysis. The gem veins occured in the gabbro xenolith zones of the verges of ultramafic rock bodies. The direct surmunding rock of the gem veins is grossularite (Qilian cui-jade). Those were formed by metasomatic alteration when the low temperature hydrnthermal solution had been flowing along the cracks in grossulallte, the mineralization Period is the late-stage of the multiple serpentinization of ultramafic rocks.