宝石矿物──钙铁榴石的物化性质研究及评价  

Study and Evaluation on Physical and Chemical Properties for a Speies of Gem Garnet──Andradite

作　　者：陈克樵 张英军[1] 於晓晋[1] 马春学[1] 

机构地区：[1]地矿部矿床地质研究所,中国地质博物馆,北京科技大学地质系,钢铁研究总院

出　　处：《岩矿测试》1996年第2期109-113,共5页Rock and Mineral Analysis

摘　　要：应用电子探针等矿物物理分析测试技术，对我国某地发现的宝石级石榴石─钙铁榴石宝石矿物进行物化性质方面的研究，并对宝石作了初步评价。In 1994, a species of gem garnet──andradite was found in China for the first time. It is not only with good quality but also with considerable scale and reserves. The density of the andradite is 3.83 t/m3 with refractive index of more than 1.83 and dispersion of 0.56.The colours are from yellow fresh-green, green wine-yellow, dark wine-yellow,orange to dark orange. The crystal size of the gem varies from x mm to 100 mm with relatively perfect crystal shape and most of them are 20～50 mm. The crystals exhibit rhombic dodecahedron shaped or cimbination of rhom bic and trapezohedron. The andradite with yellow fresh-green colour was analyzed by electron probe and its composition is as follows(w/%): MgO0.62, Al2O3 1.09, SiO2 35.45, CaO 31.39,Cr2O3 0.06, MnO 0.08 FeO 30.65,and CuO 0.29 . The chemical formula of andratite is proved to be 3CaO. Fe2O3. 3SiO2 or Ca3Fe2[SiO4]3 by electrovalent equilibrium calculation. The physicaland optical properties of andradite are only next to the best gem-diamond, but better than ruby,sapphire, emerald, chrysopal and jadeite. Its dispersion is even higher than diamond. Demantoid, a variety of andradite with good quality,can even compare favorably with the same grade of sapphire and emerald.

关 键 词：宝石 钙铁榴石 电子探针 物理性质 化学性质 

分 类 号：P578.947[天文地球—矿物学]