小秦岭金硐岔金矿床九号石英脉中自然铁的发现及研究

自然铁产于含金石英脉中,其外壳为磁铁矿。多数自然铁外壳被闪锌矿包裹,个别闪锌矿又被包裹在自然铁外壳中.按表面形态自然铁可分为两种类型:园滑状;不规则的港湾状.锯齿状。据穆斯堡尔谱峰面积法,外壳磁铁矿Fe~(+++)/Fe~(++)比值为1.4～1.7.电镜成分面扫描表明,随外壳厚度增加,氧浓度增高而硫浓度降低。不规则状自然铁外壳磁铁矿可能由黄铁矿氧化而来。

THE STUDY AND DISCOVERY OF NATIVE IRON IN NO.9 QUARTZ VEIN OF JINDONGCHA GOLD DEPOSIT, XIAOQINLING

The native iron occurs in No.9 Au-bearing quartz vein. It was included almost by the magnetite of outer crust, consisting of "bilayer structure". Many outer crusts were included by sphalerites in colour usually light yellow to brown. According to surface forms, the native iron can be divided into two types: rounded and irregularly saw-toothed or bay-like. The Mossbauer spectroscopic study of 57Fe shows that the variation of Fe3+/Fe2+ ratio is 1.4-1.7 in the magnetite of outer crust. The area scanning analysis of SEM indicates that the oxygen concentration increases and the sulphur concentration decreases with the increasing of outer crust thickness. It is considered that the magnetite of outer crust of irregular native iron has been oxidized by pyrite.