Natural Radioactivity of Laterite and Volcanic Rock Sample for Radioactive Mineral Exploration in Mamuju, Indonesia

Abstract

Mamuju is a region of Indonesia with relatively high exposure to natural radiation. Since 2012, Mamuju has been a uranium and thorium exploration area. Several mapping studies of the region have been carried out to depict NORM (naturally occurring radioactive material) areas and areas with uranium anomalies. This paper is the first study to use radioactivity measurements of laterite and volcanic rocks to determine the characteristics of radionuclides and other mineral measurements, which are essential for categorising Mamuju rocks and exploring the region as a potential mining area. The radioactivity of the samples was measured using a high-purity germanium (HPGe) detector. Furthermore, we used X-ray fluorescence (XRF) to determine the rock mineral composition. Mamuju is anomalous due to its high content of 238U and 232Th concentrations of 539–128,699 Bq·kg−1 (average: 22,882 Bq·kg−1) and 471–288,639 Bq·kg−1 (average: 33,549 Bq·kg−1), respectively. The major elements are dominant, including Fe2O3, SiO2, Al2O3, and Na2O, with several other major elements such as MnO, TiO2, and CaO.

Keywords

• uranium
• radioactive mineral
• exploration
• rocks
• radioactivity