祁雨沟金矿自然金的标型特征及其找矿意义

Typomorphic Characteristics of Native GoId from the Qiyugou Gold Deposit and Their ore-prospecting Significance

本文以２８００粒自然金的研究为基础，系统讨论了自然金的标型特征。研究指出：本矿床应具较大规模，矿区内除Ｊ＿２、Ｊ＿４角砾岩体外，其余几个角砾岩体也应有一定远景，｛１１１｝、｛１１１｝＋｛１００｝、｛１１０｝的出现可指示富矿地段，自然金晶体形态的空间分带规律可确定（岩）矿体的剥蚀深度及评价外围角砾岩体的含矿性及远景；自然金中Ｂｉ可做为找矿评价的指示元素。

The explosive-collapsed breccia gold ore deposit seems to be a major andrepresentative one among the Qiyugou type gold deposists. The ore field islocated at the Southern margin of the North China platform,Gold minerali-zation was genetically related to the evolution of the Middle-Late Yanshaniancalc-alkaline magma. The whole ore-forming process underwent vanward,major and late alteration-mineralization periods,with native gold being thepredominant gold ore mineral. This paper deals mainly with typomorphic characteristics of native gold.2800 grains of native gold have been studied by the authors by means ofnaked eye, microscopy and electron microprobe analysis.In the light of thetypolnorphic characteristics so far established,it is presumed that the brecciatype gold deposits under exploration may be considerable in scale,and that,besides the auriferous J_4 and J_2 breccia orebodies,the other breccia bodies inthe Qiyugou ore field ought to have good prospects.The existence of gold crys-tals{111},{111}+{110},{100}may indicate rich gold mineralization areas.The denudation depth of the orebod ies(auriferous breccia bodies)may becstimated with the help of the regular zoning pattern of the gold crystalforms in space. This special zoning may also be used to evaluate ore potentialand prospects of all other breccia bodies on the outskirts. Moreover,the rela-tively high content of bismuth in native gold may be taken as an indicatorfor ore prospecting and evaluation.