Studi Tipe Endapan Nikel Laterit Pada Kecamatan Bahodopi, Kabupaten Morowali, Sulawesi Tengah

Abstract

Nickel laterite deposits represent the primary source of nickel formed through intensive weathering of ultramafic rocks in tropical regions. Deposit characterization is essential for understanding nickel enrichment mechanisms and supporting more effective exploration strategies. This study aims to characterize and classify the nickel laterite deposit type within the IUP area of PT Bumi Kalaena Persada, Bahodopi District, Morowali Regency, Central Sulawesi, Indonesia. The research employed geomorphological analysis, surface geological observations, drilling data interpretation, geochemical analysis using X-Ray Fluorescence (XRF), and petrographic examination. Deposit classification was based on Ni grade distribution, mineralogical characteristics, groundwater table position, and nickel accumulation mechanisms. The results indicate that the laterite profile developed over serpentinized lherzolite belonging to the Ultramafic Complex. Nickel enrichment is predominantly concentrated within the saprolite zone, with grades ranging from 1.24% to 2.38%, accompanied by increasing MgO and SiO₂ contents and decreasing Fe concentrations. Mineralogical analysis identified hydrous Mg–Ni silicate minerals, including garnierite, talc, and serpentine, as the principal nickel-bearing phases. The groundwater table is interpreted to occur within the limonite–saprolite transition zone, where it plays a significant role in controlling nickel mobility, precipitation, and accumulation. The integration of geochemical, mineralogical, hydrogeological, and nickel accumulation characteristics indicates that the deposit is classified as a hydrous silicate type, with the saprolite zone representing the principal horizon of nickel enrichment.