湖南临武舜珑玉矿物组成及成因分析

Mineral Composition and Genesis Analysis of Shunlong Jade from Linwu of Hunan

湖南省临武县舜珑玉是一种以硬水铝石矿物为主要成分的新玉种。对它的矿物组成及成因进行研究,是地质找矿和开发利用的重要技术支撑。采用偏反光显微镜和X射线衍射仪测试舜珑玉的结构特征和矿物组成,依据成因矿物学中矿物的结构标型特征理论确定舜珑玉的成因类型,根据组成矿物的相互交代和穿插关系确定矿物的演化顺序。研究结果表明:舜珑玉主要矿物成分为硬水铝石,次要矿物为刚玉、黄玉和绢云母,变晶结构和交代结构发育。舜珑玉是含铝薄层受岩浆作用发生热接触变质和热液接触变质作用形成的,后期有硬水铝石热液充填。矿物演化顺序为:早期沉积硬水铝石→硬水铝石、刚玉→硬水铝石、黄玉→脉状分布硬水铝石→绢云母。

Shunlong jade from Linwu county of Hunan Province is a new kind of jade mainly composed of diaspore mineral.The study of its mineral composition and genesis is an important technical support for geological prospecting and exploitation.The mineral composition and structure characteristics of Shunlong jade are tested and analyzed by partial reflective microscope and X-ray diffractometer.The genetic type of Shun Longyu is determined according to the theory of structural typomorphic characteristics of minerals in genetic mineralogy,and the mineral evolution sequence is determined according to the mutual metasomatism and interlacing relationship of constituent minerals.The main minerals of Shun longyu are diaspore,the main secondary minerals are corundum,topaz and sericite.The metamorphosis structure and metasomatic structure are developed.According to the mineral composition and structural characteristics,Shun-Long-yu was formed by thermal contact metamorphism and hydrothermal contact metamorphism of aluminum-bearing thin layer under magmatic action.Later,it was filled with hydrothermal diaspore.The mineral evolution sequence is as follows:early bauxite(bauxite)is recrystallized in contact with rock mass to form bauxite with crystallized structure.Bauxite is decomposed into corundum when heated at about 500℃.Corundum is formed into diaspore or topaz by hydrothermal metasomatism and diaspore is formed into topaz by hydrothermal metasomatism.Bauxite hydrothermal fluids were inserted and filled to form bauxite veinlets.Part of diaspore is metasomatized to sericite by hydrothermal solution.