Integration of magnetic susceptibility and geological–geochemical data for volume prediction and mining priority scale of rare earth element enrichment

Rare earth element (REE) continues to be a global concern for exploration and utilize as a raw material of modern industry. This research focuses on tracing of REE sources that determine their potential, predicting REE volumes and the scale of mining priorities in an area. The samples of this study were taken from Bromo Tengger Semeru (BTS) complex that was dominated by material volcanic according to the geological map, that is, lava andesite, tephra, pyroclastic fall, laharic, pumice, volcanic deposits and volcanic soils. The determination of REE potential is measured by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The dominant REE potential in BTS, with average values, respectively, is Ce (38.82 ppm), La (29.91 ppm), Nd (22.91 ppm), Gd (17.67 ppm), Pr (10.20), Tb (8.71 ppm), Sm (4.28 ppm) and Y (18.73 ppm). The REE volume prediction was carried out by integrating the geochemical data of the REE with the geological map of the research site by multiplying the volume of total REE from measurement and the total volume of the area by mapping, dividing by one million (ppm). The predicted BTS volume is limited to the selected area above sea level. Furthermore, the scale of mining priority in the BTS area shows that the Bromo area becomes first priority and then the Semeru area as the second priority with the same pattern of Ce, Nd and Gd, although opposite pattern to La.