Characterisation of hypogene covellite assemblages at the Chuquicamata porphyry Cu deposit, Section 4500N, Chile

摘要

Covellite (CuS) has traditionally been described as a mineral formed by supergene oxidation processes although its occurrence as a hypogene mineral is well documented. However, it maybe difficult to distinguish hypogene covellite from that of supergene origin without consideration of associated minerals and geologic setting. Also, the mineralogical relationships surrounding covellite in the Cu-Fe-S system are poorly constrained with respect to temperature, particularly above 250 deg C.This thesis was planned as a first step toward the characterization of covellite, attempting to develop practical criteria for the differentiation of hypogene from supergene covellite in the Cuquicamata prophyry Cu deposit, Chile. Approximately 120 samples of ore were collected from three drill holes that intersect the major alteration zones (e.g., potassic, quartz-sericite, chloritic), within the 4500N coordinate section, recommended by mine staff to be representative of the deposit. The petrology and mineralogy of the samples were studied using reflected light microscopy, X-ray diffraction and the electron microprobe.