闪锌矿的标型特征、形成 条件与电子结构

本文阐述了我国几个不同成因矿床闪锌矿的化学成分、晶胞参数和物理性质,如硬度、密度、反射率、吸收边能量、磁化率等的特征;根据闪锌矿的内部电子结构和微量元素的晶体化学特征讨论了成分、结构与物理性质之间的相互关系;并探讨了这些标型特征在矿床成因和地质找矿上的意义。

The typomorphic features, formation conditions and electronic structure of sphalerite

This paper deals with chemical composition, lattice cell parameters and physical properties(such as microhardness, specific gravity, reflectivity, absorption edge energy and susceptibility) of some natural sphalerite from the Dachang hydrothermal cassiterite-sulfide deposit, the Lamu skarn zinc-copper deposit, some mesothermal-epithermal lead-zinc deposits including Taolin and Dongpo, and the sedimentary-reworked lead-zinc deposits in liankou and rechang.The sphalerite from Dachang and Lamu are characterized by higher contents of iron, manganese, cadmium, copper and indium(the Lamu sphalerite are also enriched with tin), that from Taolin by higher contents of cobalt and gallium, that from Dongpo by higher contents of manganese and cadmium, and that from Fankou and Rechang by higher contents of mercury and germallium and widely varying contents of trace elements. The higher tin contents of sphalerite from cassiterite-sulfide deposits can serve as an indicator in search for such hidden ore bodies.The physical properties of sphalerite are determined by trace elemen t contents, especially the content of iron. In general, with the growing contents of iron, the lattice cell parameters and reflectivity of sphalerite increase whereas the microhardlless and the absorption edge energy of sphalerite decrease. This can be explained with the help of a model for the electronic structure of sphalerite and iron-bearing spha]erite. The crystal field levels of the substituting ferrous iron are located in the sulfur nonbonding band and the forbidden band, so the covalent bonding between zinc and sulfur is stronger than that between iron and sulfur meanwhile, the increased iron makes the sphalerite more metallic.