Characteristic of Granite Alkaline Rocks Bearing Monazite and Thorite in Semelangan West Kalimantan

Abstract

The Semelangan area of West Kalimantan has the potential for radioactive minerals, namely monazite and thorite, which are concluded from the results of petrographic analysis and mineral grain analysis of granite rocks based on research that has been carried out since 1989. The petrographic data shows that the type of granite is granite and alkali-feldspar granite. Radioactive mineralization that occurs in granite (remaining magma) in addition to monazite and zircon is also found in thorite, which fills between minerals indicated by the track of alpha particles in thorite based on autoradiography results. In addition to petrographic analysis and autoradiography analysis, the presence of monazite and thorite in the study area, mineral grain analysis has been carried out which produces mineral content presentation data from 16 samples, and one of the samples containing 63% monazite mineral.