砷酸盐矿物研究及其地质找矿意义

A Study of Arsenate Minerals and Its Geological Significance to Ore Prospecting

砷酸盐矿物是主要产出于硫化物矿床氧化带中的一类较为重要的次生矿物,在自然界中已发现250多种,但在我国对该类矿物开展的研究工作较少,目前仅发现该类矿物39种。本文根据对在广西、广东、云南和湖南等地若干硫化物矿床氧化带中发现的砷酸盐矿物的研究,并综合有关研究资料,对我国产出的砷酸盐矿物的矿物学特征和形成条件进行系统的论述;根据该类矿物的形成环境和共生组合特征,初步探讨它们对揭示原生矿床类型和寻找隐伏原生矿床(体)的标志意义。

The arsenate minerals are the secondary minerals which occur mainly in oxidized zones of sulfide deposits. More than 250 arsenate minerals have been found in nature , but only 39 are found in China. One of the remarkable characteristics of arsenate minerals is that most of them are bright-coloured in green (yellow or red). These minerals commonly show fibrous, acicular, columnar, tabular and cubic crystalline forms, but, being formed in surface conditions, they often occur in botryoidal,kidney and spherulitic aggregates with low degrees of crystallization. These minerals are of complicated chemical compositions, consisting of poly-metallic elements and molecular groups, especidly H2O, OH or halogens. They are closely related to arsenopyrite, As-bearing minerals, chalcopyrite, pyrite, galenite etc. during their formation and development, generally formed in an environment of weakly acid-neutral oxidizational media (pH=3~7) in warm, humid and rain tropic-subtropical zone, and with the carbonatites as wall rocks of the deposit. Arsenate minerals are one of the important products at the latest stage of development of oxidized zones of sulfide deposits. Their paragenic types are often closely related to the mineral compositions of the primary ores. So, arsenate minerals may be used as one of the indicators for seeking Cu (Sn)-Pb-Zn poly-metallic sulfide deposits in the gossans and oxidized zones of well-developed arsenate minerals.