Core logging is the systematic, detailed recording and documentation of the physical, geological, and geotechnical properties of drill core samples recovered from boreholes drilled during mineral exploration and mining operations. In bauxite, gold, iron ore, and diamond mining, core logging is one of the most fundamental and critical activities in the resource estimation process, providing the primary data used to build geological models, estimate mineral resources, and plan mine development. Core logging is carried out in a core shed or core yard by qualified geologists who examine each tray of drill core and record a comprehensive range of parameters, including rock type (lithology), mineralogy, degree of weathering and alteration, structural features (fractures, faults, bedding planes, foliation, joints), colour, texture, grain size, and the presence of any mineralisation or ore indicators. In addition to geological logging, geotechnical logging captures information such as rock quality designation (RQD), fracture frequency per metre, fracture condition (roughness, infill material, alteration), and rock strength estimates — data that is essential for mine design, slope stability analysis, and underground support design. In gold mining, core logging includes identification of sulphide mineralisation, quartz veining, and alteration zones that indicate proximity to ore. In bauxite logging, the focus is on identifying gibbsite, boehmite, and diaspore content and the thickness of the bauxite horizon. In iron ore logging, the distinction between high-grade hematite and low-grade magnetite or BIF is critical. In diamond exploration, core logging documents the presence of kimberlite indicator minerals. All logging data is entered into a geological database (such as Datamine, Leapfrog, or acQuire) for subsequent processing and modelling.
