江西东乡铜矿中含铜硫化物的几种 微结构及其地质意义

根据对江西东乡铜矿矿石矿物的光学显微镜以及电子探针的研究，发现了该矿石中久辉铜矿与蓝辉铜矿呈页片状或互界状的交生构造，同时还存在着斑铜矿-蓝 辉铜矿的环带状构造。这两种构造中的蓝辉铜矿在成分上有明显差异，前一种构造中的蓝辉 铜矿不含Fe，而环带构造中的蓝辉铜矿含一定量的Fe。讨论了两种蓝辉铜矿各自的形成机制及其地 质意义。

Some Microstructures of Copper Sulfides in Dongxiang Copper Mine, Jiangxi Province, and Their Geological Implications

Based on the optical microscopy, electron microprobe studie s and X-ray powder diffraction analysis it is revealed that the djurleite and dig enite are freguently found in copper ores of Dongxiang Copper Mine, Jiangxi Prov ince. The digenite occurs as the lamellae or lens in the djurleite. These two minerals also appear together with a mutual boundary texture. Their average chemical formulas can be expressed as Cu 1.827Zn 0.004Ag 0. 001S and Cu 1.929Fe 0.002Zn 0.003Ag 0.001S, respectively . Near the area of the metasomatic relicts of pyrites the bornite-digenite z oning is commonly seen. The core is composed of bornite, whereas the digenite oc curs at the rim. The optical property and chemical composition of the digenites in these two different textures are different. These two kinds of digenite are b oth blue gray in reflection color, but the reflection color in digenite intergro wn with djurleite is lighter than that in the zoning one. As for the composition s the digenite intergrown with djurleite does not contain iron, whereas in the z oned digenite the iron contents range from 2.8%(wt.) to 9.1%(wt.). The iron cont ents also decrease toward the rim of the zoning, and the color is getting lighte r under reflected microscope with the iron contents decreasing. The two texture s mentioned above represent two kinds of cooling texture of Cu-S and Cu-Fe- S systems respectively. The intergrowth between the iron-free digenite and the dj urleite was produced by exsolution of high digenite solid solution upon coo ling. The zoning texture of bornite and Fe-bearing digenite is produced by the segregation of the Cu 1.8S-CuFeS 4 solid solution in the disequilibrium c ondition. It is believed that it represents a kind of texture that forms with ra pid cooling.