中国各产地软玉的化学成分分析

Chemical Composition Analysis of Nephrites from Different Localities in China

软玉的主要化学成分是SiO2, MgO和 CaO, 类质同象替代使其还含有少量的 FeO, K2O, Na2O和Al2O3等杂质成分。通过对中国各产地软玉晶体化学式的计算及化学成分之间相互关系的分析, 发现其平均化学成分与透闪石的理论值接近, 说明了软玉的主要矿物组成是透闪石。化学成分在一定程度上可以反映软玉的产地及品种特征, 尤其是Fe2+的类质同象替代使 w(FeO)成为区分软玉产地和品种的重要标志。

The main chemical compositions of nephrite are SiO_2, MgO and CaO, and the isomorphous replacement makes it contain a little amount of FeO, K_2O, Na_2O, Al_2O_(3) and so on. By calculating crystal-chemical formulas and analyzing the relationships among the chemical compositions, It can be found that the average chemical compositions of nephrites from different localities in China are very close to theoretical value of tremolite. The result indicates that the main mineral of nephrite is tremolite. In addition, the chemical compositions can also reflect features of localities and the species to some extent. The isomorphous replacement of Fe^(2+) makes w(FeO) to be the important indicator for identifying the locality and species of nephrite.