CHARACTERISTICS OF LATERITES NICKEL DEPOSITS AND RARE EARTH ELEMENTS IN GEBE ISLAND, CENTRAL HALMAHERA, NORTH MALUKU

• Main Author: Rafif Abidin, Rabbani
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69638
• Institution: Institut Teknologi Bandung

Gebe Island is indicated to have nickel and its accompanying metal prospects due to the presence of ultramafic rocks. The research area is administratively located on Gebe Island, Central Halmahera, North Maluku (area 4,73 km2). The research area is a free area (greenfield area) where there is no mining business activity. This study is conducted to determine the characteristics of laterite, bedrock and their correlation with REE (Rare Earth Elements) abundance. Data used are DEM (Digital Elevation Model), field, and assay. Field data consists of 12 rock samples and 30 drill points with 91 samples of laterite deposits. The assay data consists of XRF (X-ray Fluorescence), AAS (Atomic Absorption Spectrophotometer), and ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry) data (91 laterite samples and 12 bedrock samples in the study area). The characteristics of laterite deposits in the study area are generally distinguished based on the characteristics of the bedrock, namely serpentinized dunite and olivine gabronorite. Laterite deposits profile in study area consists of red limonite, yellow limonite, and saprolite. The red limonite zone is characterized by a relatively high Fe2O3 content and a strong degree of lateritization, the yellow limonite zone is characterized by a relatively high Al2O3 content and weak-strong degree of lateritization, the saprolite zone is characterized by a relatively high MgO content and SiO2 content. The study area based on topography is divided into hill slope and lowland basin. The hill slope Ni ore zone is found in upper red limonite and lower red limonite to upper saprolite and has moderate to very strong positive correlation with Cr2O3, Co, and Al2O3. The lowland basin Ni ore zone is found in lower red limonite and has very strong positive correlation with Fe2O3, MgO, and Cr2O3. The type of lithology in the study area influences the enrichment of Ni elements in the study area. The Ni content in the ore zone in the dunite-dominated area has the largest content of 0,125% and the smallest 0,1%?Ni?0,125%. Meanwhile, the Ni content in the ore zone in the area dominated by olivine gabronorite has a Ni content of ?0,07%. In general, Ni laterite deposits in the study area show relative enrichment of REE to bedrock and LREE content is higher than HREE content. Based on Spearman correlation, the main controller of LREE(La-Eu) and HREE(Gd-Lu) enrichment is Fe mineral with spearman coefficient value between LREE(La-Eu) and HREE(Gd-Lu) with Fe2O3 is 0,64 – 0,83. While the main controller of Sc enrichment is Al mineral with Spearman coefficient value between Sc and Al2O3 is 0,59.