Identifikasi Batuan Sumber dan Deliniasi Sebaran Endapan Aluvial Mengandung Monasit di Kabupaten Bangka, Provinsi Kepulauan Bangka Belitung

Monazite (Ce, La, Th, Y (PO4)) is mineral, which has high
economical value that contain radioactive and rare earth element. In Indonesia monazite formed in acid to medium igneous rocks, moderate to high degrees metamorphic rocks, sedimentary rocks especially sandstones, and alluvial deposits. This study is purpose to observe
the source rocks and alluvial deposit that have possibility to contain monazite mineral in Bangka Region by geological mapping and rock/soil radioactivity measurement on 1:50.000 map scale, continued with heavy minerals and rock sampling for geochemical and petrography analysis. Geologically of Bangka-Belitung that composed by Klabat Granite, Tanjunggenting
Sandstone and Alluvial deposits. Based on petrography analysis result shown that granite compose by quartz, plagioclase, k-feldspar, muscovite, monazite, zircon, biotite, serisite, chlorite, opaque minerals, and iron oxidized. Radioactivity measurement result shown of Pemali Complex Unit with radioactivity measured 35c/s – 290c/s, Tanjunggenting Sandstone Unit with radioactivity measured 40c/s – 75c/s, Klabat Granite Unit with radioactivity measured 200c/s – 600c/s, Ranggam clay-sand unit with radioactivity 75-125 c/s, and Alluvium deposits Unit with radioactivity measured 20c/s – 200c/s. According the result of radioactivity measurement,
geochemical analysis shown the alluvial deposit that contain monazite is the alluvial deposits
which correlated or spreading around the source rock (granite)