菲律宾达沃砂金矿中金汞矿物研究及其找矿意义

Mineralogical Characteristics of Gold-mercury Mineral in the Davao Gold Placer of Mindanao Islands,Philippines and Its Prospecting significance

本文系统研究了菲律宾棉兰老岛达沃砂金矿的矿物组合、金汞矿物的矿物学特征,认为随着金汞矿物中汞含量成分增加,金-汞系列矿物反射力具有由强-弱-强的变化特征,同时矿物硬度也随着减少。但是,当汞含量增加到相当比例时,尤其是晶体结构为等轴晶系时,其硬度却逐渐变大。笔者研究发现,金汞齐和r-汞金矿只是作为自然金或含汞自然金的矿物镶边而存在。总体上,汞的含量从金粒边缘向中心是逐渐减少的,但金粒边缘比中间低。结合成矿地质背景分析,笔者认为菲律宾应该有可能存在伴随超基性-基性岩浆活动形成的铂、铬等幔源矿床,也极有可能发现大型或特大型金、汞和多金属矿床,以及金、铂等滨海砂矿床。

Mineral assemblage and mineralogical characteristics of gold-mercury minerals in the Davao Placer of Mindanao Islands,Philippines were systematically studied in this paper.Results show that,with the increasing mercury content in gold-mercury minerals,their reflecting power exhibits variations in the sequence of strong →weak → strong,in contrast to the decrease of mineral hardness.However,when the content of mercury reaches a definite proportion,especially when the crystal displays isometric crystal texture,its hardness increases.We also find that goldmalgam and r-goldmalgamite just occur as natural edge of gold-mercury mineral grains.Overall,mercury content gradually reduces from the edge to the centre of gold-mercury mineral particles,but that in the edge of grains is lower than that in the middle.With a combination of the analysis of metallogenetic background,this paper suggests that there are mantle-derived platinum and chromium deposits in the region,which are accompanied by ultramafic-mafic magmatism,and large and ultra-large scale gold,mercury-polymetallic deposits,as well as coastal placer of gold and platinum are also likely.