Geology of Nickel Deposit
Nickel
ore deposits are formed through various geological process and conditions, and
they are typically associated with specific types of rock formations and
mineralization events. The common geological process that lead to the formation
of nickel ore deposits include: Magmatic processes, hydrothermal processes,
sedimentary processes and Lateritic weathering. Lateritic nickel ore deposits
typically formed in tropical or subtropical climates through leaching of
ultramafic rocks, such as serpentinized peridotites. Lateritic nickel deposits
are characterized by their typically low-grade nickel content and are
predominantly found in Indonesia and New Caledonia. The following picture
showing the lateritic nickel strata within the excavated area in Sorowako site
of PT.Vale Indonesia
Nickel Exploration
Exploration
of nickel ore typically involves a combination of geological, geophysical, and
geochemical methods to identify prospective areas for further investigation. Multispectral
and hyperspectral remote sensing data can provide valuable information about the
mineralogical and chemical composition of rocks, which can aid in identifying
prospective areas for further exploration.
Nickel Geophysics
Some common
geophysical methods used in Lateritic Nickel Exploration include Electrical
Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), Magnetic and
Electromagnetic surveys. These methods can help identify the subsurface
features and the distribution of nickel laterite. The following sections
showing the equivalence of the ERT profile (bottom) and the excavated profile
at Anoa North, PT.Vale Indonesia.
Nickel Drilling
Drilling
involves the extraction of rock cores or samples from the subsurface to obtain
direct information about the geology and mineralization of the target area.
Diamond drilling is commonly used in nickel exploration to obtain high-quality
core samples for detailed geological, mineralogical, and geochemical analysis.
Drilling can help confirm the presence of nickel mineralization, determine its
grade and thickness, and provide valuable data for resource estimation. The following picture showing the drilling that contained nickel grade at various depth.
3D Modelling of Nickel
Geologic modeling involves the integration of various data
sets, such as geological, geochemical, and geophysical data, into a
three-dimensional (3D) model of the subsurface geology. Geologic modeling can
help visualize and interpret the spatial distribution of rocks, structures, and
mineralization, and can assist in identifying favorable areas for nickel
mineralization. Advanced software and techniques, such as Geographic Information
Systems (GIS) and 3D modeling software, are commonly used in geologic modeling.
Resources Estimation
Apply various resource estimation techniques, mainly using geostatistics,
to assess the quantity and quality of the nickel laterite deposit. Common
methods include Ordinary Kriging, Inverse Distance Weighting, and Gaussian
Simulation. Then, Validate the 3D model and resources estimates with additional
drilling or sampling to ensure the accuracy.