内蒙古哈达门沟金矿床单矿物金浸出实验研究及其地质意义

哈达门沟金矿床产于华北克拉通北缘西段，形成于伸展构造背景中，成矿流体富钾高碱且氧化性强，矿石建造中铁氧化物含量高，并且可见铁氧化物被硫化物交代的现象。文章拟揭示金在铁氧化物中的含量和赋存状态，并探讨金矿床成因。对哈达门沟金矿3种类型矿石中的黄铁矿、铁氧化物(磁铁矿和赤铁矿)单矿物进行金、铁浸取实验，结果表明：铁氧化物含金较高；黄铁矿中的金和铁的浸出曲线不同步，金浸出率与铁浸出率呈负相关，表明黄铁矿中的金主要以颗粒金形式存在；铁氧化物中金、铁同步浸出，浸出率为正相关，表明铁氧化物中的金主要以品格金和(或)胶体吸附金形式存在。哈达门沟金矿床的上述特征均表明其具铁氧化物型金矿床的特点。

An Experimental Study of Gold Leaching from Host Minerals of Hadamengou Gold Deposit and Its Geological Implications

Located in the western part of the northern margin of the North China craton, the Hadamengou gold deposit is of hydrothermal type related to alkaline magmatism. Leaching of Au from pyrite and iron oxides (magnetite and hematite) in three main kinds of ores shows that Au and Fe were dissolved simultaneously from iron oxide (hematite) and that their solubilities are positively correlated. This means that gold is mainly chemical-bonded (lattice gold) and/or colloidal-adsorbed in iron oxides. As to the pyrite, on the contrary, gold extraction obviously lags behind iron, and the solubility of gold shows negative relationship with that of iron. This indicates that Au is mainly hosted as grains of elemental gold (or native gold) within pyrite. Previous studies have revealed that the Hadamengou gold deposit is characterized by intense K-feldspathization and high content of iron oxides occasionally replaced by sulfides, which is probably attributed to the oxidation of K-enriched alkaline fluids under an extensive geodynamic setting. These geological features, together with the high Au content of iron oxides, may suggest that this deposit is the first iron oxide type gold deposit ever discovered in China.