云南麻栗坡祖母绿的矿物包裹体特征研究

A study of mineral inclusions in emeralds from Malipo,Yunnan Province,China

采用偏光显微镜薄片观察、电子探针及背散射图像、阴极发光等方法,分别对伟晶岩矿脉和顺层剪切带矿脉两种产出状态的云南麻栗坡祖母绿进行了系统的包裹体特征研究。结果表明,云南麻栗坡祖母绿具有产地特征的包裹体有黑色镁电气石、含钒的白云母、具有环带的钾长石、毒砂、镁质黑云母、白钨矿包裹体。伟晶岩脉和顺层剪切带中的祖母绿均含有钾长石、钠长石、电气石、萤石、祖母绿(绿柱石)、黑云母、榍石、磷灰石、黄铁矿、绿泥石、绿帘石包裹体。白云母、方解石、石英、锆石、毒砂、闪锌矿、方铅矿、透辉石仅出现在伟晶岩脉中的祖母绿包裹体中;而白钨矿仅出现在顺层剪切带中的祖母绿包裹体中。对云南不同产状祖母绿矿物包裹体的研究不仅对祖母绿的产地鉴定具有宝石学意义,也对揭示云南麻栗坡祖母绿的成因类型具有重要意义。

In this research,mineral inclusions in emeralds from Malipo,Yunnan Province,are studied by polarized microscope,electron probe(EPMA),and cathodoluminescence(CL).The results show that there are several kinds of mineral inclusions which can be considered as origin characteristics in emeralds from Malipo,Yunnan Province,such as black dravite,vanadium muscovite,zonal feldspar,arsenopyrite,magnesium biotite,scheelite.Both in pegmatite veins and shear zone veins,emeralds contain feldspar,albite,dravite,fluorite,emerald(beryl),biotite,sphene,apatite,pyrite,chlorite,epidote.Inclusions only appear in emeralds from pegmatite veins are muscovite,calcite,quartz,zircon,arsenopyrite,sphalerite,galena,diopside.Inclusion only appears in emeralds from shear zone veins is scheelite.This research on different inclusions in emeralds from pegmatite veins and shear zone veins is meaningful not only for emerald identification of origin,but also reveals the genetic type of Yunnan emeralds.