Core Sample
A cylindrical rock sample obtained by diamond drilling, used to analyze subsurface geology and mineral content.
Detailed Definition
A core sample is a cylindrical section of rock extracted from the earth using a diamond drill. Core samples provide detailed information about subsurface geology, mineralization, and rock properties.
Diamond drilling process: - Hollow drill bit with diamond cutting surface - Rotates and cuts through rock - Core preserved inside drill string - Retrieved in segments (core runs)
Core sizes (common diameters): - NQ: 47.6mm (most common for mineral exploration) - HQ: 63.5mm (larger samples, better recovery) - PQ: 85mm (geotechnical applications) - BQ: 36.5mm (rapid reconnaissance)
Core logging: Geologists examine and record: - Rock types and contacts - Mineralization and alteration - Structural features (fractures, faults) - Core recovery and RQD (Rock Quality Designation) - Sample intervals for assay
Core storage: - Stored in core boxes (typically 3-5 rows) - Labeled with hole ID, depth, orientation - Preserved for future reference - May be photographed and CT-scanned
Core drilling is the primary method for evaluating mineral deposits and developing resource estimates.
Related Terms
Mineral Resource
A concentration of minerals with reasonable prospects for economic extraction, classified as inferred, indicated, or measured.
Assay
A chemical test performed on ore or rock samples to determine the concentration of valuable minerals.
Grade
The concentration or proportion of valuable mineral content in ore, expressed as percentage or grams per tonne.
Mineral Deposit
A naturally occurring concentration of minerals in the earth's crust that may be of economic interest.
Exploration
The systematic process of searching for mineral deposits through geological, geophysical, and geochemical methods.