Identification of mineral characterization and alteration types in primary tin deposits of oxide skarn type in Batubesi mining areas by petrographic analysis and grain counting analysis

Abstract

The presence of primary tin ore on Belitung Island can be found in several areas with varying amounts of presence. One area that has the potential is the Batubesi TB area, Burung Mandi Village, Damar District at East Belitung Regency. This research aims to identify mineral assemblages and alteration types in oxide skarn deposits. The methods used are outcrop observation, sampling, and mineralization-alteration identification. Testing of rock samples through petrographic analysis is to identify minerals through their polarization optical properties and GCA analysis (Grain Counting Analysis) is to determine specific types of minerals that cannot be seen through petrographic analysis. Macroscopically, oxide skarn deposits have a greenish-brick red, black appearance which is dominated by ore minerals (iron oxide, iron carbonate, and iron sulfide), and in some parts chlorite mineral dissemination. Based on the observation result of the optical properties of the rock samples, metallic minerals other than those that have been directly identified were found, such as ilmenite, siderite, cassiterite, and chlorite. The results of the GCA analysis indicate the presence of cassiterite, pyrite, quartz, siderite, hematite, and limonite minerals. Based on these minerals, it can be seen that the type of alteration in the study area is skarn alteration.