黄铁矿载金的原因和特征

对102个金矿床载金矿物的统计表明，黄铁矿是最普遍最重要的载金矿物。造成黄铁矿成为主要载金矿物的原因，有三个矿物学方面的因素，即结构因素、成核因素和电化学因素。结构因素表现在黄铁矿晶体结构中存在对硫 ［S2］2－，对硫 形成过程中对金离子具还原效应。成核因素表现在自然金成核常选择原子排布与之最接近的黄铁矿表面为衬底，以降低成核能。电化学因素表现在黄铁矿的热电性导致金离子在其表面发生电化学反应而沉淀结晶。对黄铁矿载金能力的分析表明，细粒、它形、裂隙发育程度高、As和Sb含量高以及P型的黄铁矿载金能力高，自形黄铁矿中的{210}、S面{100}及其聚形晶的载金能力高。

Genesis and Characteristics of Gold Hosted by Pyrite

Many geological facts show that pyrite is an important gol d-hosting mi neral in gold deposits. Many geologists have studied the genesis of this phenome non in the past based on the geochemical properties of elements and adsorption e xperiments. In this paper, the genesis and characteristics of gold hosted by pyr ite is studied mainly in the light of mineral structures and properties as well as crystal growth of pyrite and native gold so as to comprehend this phenomenon further. According to the statistical data of gold-hosting minerals from 102 gold deposi ts with different genetic types, there are more than 19 species of minerals cons idered as gold-hosting minerals, which include sulfides, oxides, silicates, car bonates and sulfates. Of these gold-hosting minerals, pyrite is the most common and most important gold-hosting mineral in gold deposits. The number of gold d eposits with pyrite as gold-hosting mineral is up to 98% of the total 102 gold deposits, and the number of gold deposits with pyrite as major gold-hosting min eral is about 85%. The cause for pyrite to be a major gold-hosting mineral comprises three mineral ogical factors: the structural factor,nucleation factor and electrochemical fact or. The biatomic sulfur S 2]- 2- in the crystal structure of pyrite may cause the reduction of Au- and Au- 3 to Au-0 during the biatomic sulfur formtion. The crystal nucleation of native gold usually selects the pyrite surf ace as backing in order to decrease the energy barrier of crystal nucleation, be cause the arrangement of atoms in pyrite is closest to that in native gold. The electrochemical reaction caused by the thermoelectricity of pyrite may take plac e on the pyrite surface, which in turn may reduce the ionic gold to Au-0 to cry stallize. Analysis on the gold-hosting capacity of pyrite shows that the fine-grained,an hedral, cracked pyrites with higher contents of As and Sb, and with P-type the rmoelectricity have higher capacity of gold-hosting. The euhedral pyrites with {210}, step-face {100} and combined form also have higher capacity of gold-hos ting.