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.