陕西省金堆城钼矿床碲、铋矿物的赋存状态 及其地质意义

本文利用电子探针微束分析技术,对陕西省华县金堆城斑岩型钼矿床中产出的矿物组成及赋存状态进行了较为系统的研究,经研究发现,矿床中有较多碲、铋矿物的存在.主要包括:碲银矿、针硫铋铅矿、含硫铋铅银矿及含铋、银-方铅矿.碲银矿主要呈半自形粒状,与针硫铋铅、含硫铋铅银矿及含铋、银-方铅矿共生并被黄铁矿所包裹;针硫铋铅矿呈自形粒状被黄铁矿包裹并与黄铜矿、碲银矿等矿物共生;含硫铋铅银矿有两种不同的产出状态:第一,以自形粒状形态与黄铜矿、闪锌矿及碲银矿共生形成复杂共生体.第二,以较小的颗粒被黄铁矿包裹,含铋、银-方铅矿呈自形-半自形粒状与黄铜矿、闪锌矿、碲银矿及含硫铋铅银矿密切共生.其中,碲银矿的出现暗示了成矿流体是幔源成因;含铋、银-方铅矿从核部到边部Ag、Bi的含量有逐渐上升,而Pb的含量有逐渐下降的趋势,反映出了其晶格中发生了Ag+、Bi3+替代Pb2+的作用.

Occurrence and geological significance of telluride or bismuth minerals in the Jinduicheng porphyry Mo deposit,Shanxi Province

A systematic study was carried out by means of the Electron Probe Micro Analysis ( EPMA) on mineral composition and occurrence state of Jinduicheng porphyry Mo deposit, Shanxi Province. The results show that there are some tellurium or bismuth minerals in the deposit which mainly include:hessite, aikinite, schirmerite and Bi-and Ag-bearing galena. Hessite wrapped by pyrite mainly forms subhedral grains intergrowth with aikinite, schirmerite and Bi-and Ag-bearing galena. Aikinite covered by pyrite usually forms euhedral intergrowth with chalcopyrite and hessite. Schirmerite has two states:In euhedral granular with chalcopyrite, sphalerite and hessite constitutes complex symbiont;In small particle surrounded by pyrite. Bi- and Ag- bearing galena mainly forms euhedral-subhedral grains intergrowth with chalcopyrite, sphalerite, hessite and schirmerite. The emergence of hessite implies that the ore-forming fluid is mantle origin. In the Bi- and Ag-bearing galena, from the core to the margin, the content of Ag and Bi tends to increase, while the content of Pb gradually declines. The phenomenon reveals that Ag+, Bi3+replace Pb2+ in Bi- and Ag-bearing galena.