Mineralogy and chemistry over a cycle of oil shale deposition in the Brick Kiln Member, Rundle deposit, Queensland, Australia

Abstract

Chemical and semi-quantitative mineralogical analyses have been made for ore type samples over a typical cycle of oil shale deposition within the Brick Kiln Member, Rundle oil shale deposit. The geochemistry and mineralogy were similar throughout with differences mainly following oil shale grade rather than ore type. The main minerals included montmorillonite, quartz, feldspars, calcite, magnesian siderite and pyrite. Trace-element abundances were similar to those for an average shale. All samples were analyzed for a comprehensive range of major and trace elements. Correlation techniques, selective leaching procedures, X-ray diffractometry and electron microprobe analyses were used to establish geochemical associations and specific mineralogical residences for elements important in processing and waste disposal. S, As and Ni are mainly associated with pyrite and to a lesser extent with the kerogen. Mn occurs in the carbonate minerals calcite and magnesian siderite. The chemical composition of magnesian siderite differed in some samples and warrants more study as a possible indicator of depositional or diagenetic environments.