土岭-石湖金矿床黄铁矿找矿矿物学研究

PROSPECTING MINERALOGY OF PYRITE IN TULING-SHIHU GOLD DEPOSIT

河北省土岭-石湖金矿床属岩浆热液石英脉型成因类型.黄铁矿为主要载金矿物之一,其化学成分、形态和电子-空穴心特征具有指导找矿的意义.围岩中黄铁矿富含Co、Se、P;矿体内黄铁矿除富含成矿元素外还富含As、Bi,As和Bi含量随矿体埋深变化呈近直线型.本矿区黄铁矿形态有五角十二面体、立方体、前二者的聚形及和八面体的聚形.围岩中黄铁矿以含八面体的聚形为特征;矿体内的晶形变化规律(上-下):五角十二面体-立方体-聚形,聚形中八面体的出现是在围岩和矿体下部,且所在矿石含金性差.黄铁矿既有空穴心型又有电子心型导电类型.侧向上,矿体黄铁矿Vnp值(补偿电动势)最大,两侧围岩则近对称地减小.同一石英脉中的矿体黄铁矿Vnp值纵向变化明显,Vnp值随矿体埋深增加而减小,黄铁矿中的Sb、As、Co、Ni是影响其导电性的主要因素,Sb、As使其产生空穴心,Co、Ni产生电子心.黄铁矿的形态、成分和电学性质可以圈定矿体,预测矿体埋深,为寻找深部矿化远景提供依据.

Tuling-shihu auriferous quartz vein-type gold deposit is of magmatic hydrothermal origin. Pyrite is one of the major gold-carriers in the deposit, whose chemical composition, form and pyroelectricity are significant in gold prospecting. The pyrite is complicated in composition. Those in the wall rooks are enriched in Co and Ni whereas those in the ore bodies exhibit enrichment of As, Bi as well as gold. The axis zoning is marked by (Au)-As-Zn-Cu-Pb-Ni-Co-Bi, where As and Bi show linear correlation with the burried depth of ore bodies. The forms of Pyrite in the deposit comprise pcntagnal dodecahedron, cube, combination of them and octahcdron. pyrite in the wall rocks exist chiefly in combination form containing octahedron whereas those in ore bodies show regular variation from upper to lower marked by: pentagnal dodecahedron-cube-combination. The combination containing octahedron is found in wall rocks and lower portion of ore bodies where ore grade is low. The conductivity of the pyrite consists of hole-center and electron-center type, therefore compensation voltage (Vnp) is introduced in the disscusion. Laterally, Vnp of Pyrite decreases asymetrically outwards from ore bodies. Ore bodies is characterized by positive value. Along axis of ore bodies Vnp decreases with the increas of burried depth, which can be described as: D=-207.945+8.53 Vnp(r=0.9871 >rc==0.81). This fomula can be used in predicting burried depth of ore bodies, which has been proved reliable by drilling. Sb, As, Co and Ni are major impurities affecting pyrite's conductivity. Sb amd As reesult in generatoin of hole-center whereas Co amd Ni cause electron-center. The form, composition and pyroelectricity of pyrite can be used in defining ore bodies predicting burried depth, thereafter can provide evidences to gold prospecting in the depth.