哈萨克斯坦伊特穆伦硬玉岩的矿物学特征

硬玉岩是一种较为少见的高压低温变质岩,不仅具有重要的科研价值,也是一种名贵的玉石材料。本文对产于哈萨克斯坦卡拉干达州伊特穆伦矿区的硬玉岩进行了岩相学观察和矿物化学成分分析,并与缅甸、俄罗斯和危地马拉的硬玉岩进行对比。结果表明,哈萨克斯坦硬玉岩主要组成矿物为硬玉、绿辉石以及少量方沸石和钠沸石,具有粒柱状变晶结构,硬玉矿物的平均化学成分为w(SiO2)=58.38%,w(Al2O3)=21.88%,w(Na2O)=12.69%,w(CaO)=3.40%,w(MgO)=2.58%,w(FeO)=0.29%。不同产地样品中绿辉石和硬玉的SiO2含量相差不大。哈萨克斯坦样品中绿辉石Na2O和FeO的含量略低于缅甸、俄罗斯和危地马拉,MgO和CaO稍高于其它3个产地,硬玉MgO和CaO略高于其它3个产地。

Mineralogical characteristics of the Itemurun jadeitite from Kazakhstan

Jadeitite is a relatively rare metamorphic rock formed at high pressure and low temperature.It is not only a material with value for scientific research,but also a kind of precious jade material.In this paper,the jadeitite from the Itemurun mining area,Karaganda,Kazakhstan,was selected to carry out detailed petrographic observation and mineral chemical composition analysis in order to make comparison with jadeitites from Myanmar,Russia,and Guatemala.The results show that the main constituent minerals of the jadeitite in Kazakhstan are jadeite,omphacite with a small amount of natrolite and analcime.It has granular and columnar crystalloblastic structure.Its average chemical composition is 58.38%of SiO2,21.88%of Al2O3,12.69%of Na2O,3.40%of CaO,2.58%of MgO,and 0.29%of FeO.The SiO2 contents of omphacites and jadeites from different areas are very similar.The contents of Na2O and FeO of the omphacite samples from Kazakhstan are slightly lower than those from Myanmar,Russia,and Guatemala,but their MgO and CaO contents are slightly higher than those from other three area.The MgO and CaO contents of jadeite samples from Kazakhstan are slightly higher than those from other three areas.