湖北嘉鱼蛇屋山金矿氧化带粘土矿物的显微特征研究

MICROSCOPIC CHARACTERISTICS OF THE CLAY MINERALS IN THE OXIDIZED ZONE OFSHEWUSHAN GOLD MINE IN JIAYU, HUBEI

蛇屋山金矿氧化带中粘土矿物主要为高岭石、埃洛石和伊利石。电子显微镜下，高岭石的晶体自形程度差（呈不完整的假六方片状）溶蚀现象显著（普遍形成港湾状、浑圆状）；埃洛石晶体多呈管状、棒状（管套管状、卷筒状）以及板片状；伊利石呈超微细颗粒集合体（不规则的鳞片状、浑圆状及板条状等）．根据能谱分析（粘上矿物）尤其是高岭石晶体的边缘附有极为细小的石英、铁及胶体金粒，这些特征表明，氧化带经历了长期强烈的风化作用。电子显微镜的揭示表明，由于氧化带岩石疏松，裂隙发育，在长期地表水的淋滤作用下，高岭石可以水化而形成埃洛石。根据Ｘ光衍射资料及野外地质特征，氧化带中大量高岭石可能来源于伊利石的进一步风化。

Kaolinite, halloysite and illite are the major clay minerals in the oxidized zone of Shewushan gold mine. Under the electron microscope, it is revealed that the kaolinite crystals are low automorphic and distinctly corroded, the halloysite crystals are mostly in shapes of tube, rod and tabular-flake, and illites are in ultramicrograin aggregate. Based on the energy spectrum analysis, it is found that the margin of the kaolinite crystals are atteched with tiny particles of quartzs, ferric oxide and colloidal gold. All of these characteristics indicate that the oxidized zone has experienced a long term strong weathering. According to the XRD data, the observation under the electron microscope, as well as the field geological characteristics, it is identified that, in the oxdized zone, with long term leaching effect of the surface water, the kaolinite can be hydrated into halloysite on account of the porous rocks with welldeveloped fissures, and mass of the kaolinite may be source from the further weathering of the illite.