巴基斯坦的宝玉石新品种:山南矽卡岩(Sannan-Skarn)

A New Deposit of Complex Fine-Grained Rocks from Western Pakistan:Sannan-Skarn

在巴基斯坦西部发现了一种复杂的细粒宝玉石矿床。其产出的石材以其或浓或淡的绿色为特征,主要致色元素为铬。此类岩石的矿物组成在小的产出范围内亦有很大的变化,珠宝学家尚未完全了解其组成矿物(已知包括水钙铝榴石,透辉石,霓石,蓝透闪石,针纳钙石,绿泥石,钠沸石与方钠石等等)。以岩石学分类论,该类岩石为矽卡岩,一种经原岩交代变质作用后形成的岩石,通常为钙质硅酸岩。山南(Sannan)是产于此新矿床的矽卡岩的特定名称。

A new deposit of complex fine-grained rocks was found in Western Pakistan. The material is characterised by its more or less green colour, due to chrome. The mineral com-ponents vary strongly in short distances and the minerals （hydrogrossular, diopside, ae- girine, winchite, pectolite, chlorite, natrolite, sodalite etc. ） are not well known by gemmol- ogists. A common term to name the material is skarn, as it describes a rock formed by meta- somatic replacement of a parent rock, commonly a calc-silicate rock, transformed in a meta- morphic process. Sannan is a specific modifier that specially describes the skarn from the new occurrence.