Wednesday 22 July 2026
A drill core photograph is the only complete visual record of the core before it is cut, sampled, and partially consumed by the assay process. In a well-run programme, the photograph serves as a permanent geological document: a reference for re-logging, a data source for machine learning analysis, and an audit trail that a competent person can rely on when reviewing a resource estimate years after the drilling campaign ended.
In too many programmes, core photography is treated as a low-priority task delegated to whoever is closest to the camera. The cost of that attitude is invisible until someone needs the photographs for something beyond a project presentation, and discovers they are inconsistent, poorly lit, or missing critical metadata.
1. Photograph core before cutting, not after
Once the diamond saw cuts through, the full cross-section is gone. Textures, lithological contacts, alteration boundaries, and structural features that span the full diameter of the core are only visible in the intact state. CIM best practice guidelines recommend photographing core prior to splitting as part of the standard logging workflow.
Photographing cut core as the primary record loses information that cannot be recovered, regardless of camera quality. The half-core remaining after sampling shows only one face of each feature, and the orientation context is diminished. If time pressure forces a choice between a pre-cut and a post-cut photograph, the pre-cut photograph is the higher-value record.
2. Control the lighting
Outdoor photography in variable sunlight produces inconsistent colour, shadow artefacts, and glare on wet core surfaces. An indoor setup with high-CRI LED lighting (colour rendering index above 80, ideally 80-95) and diffusion panels eliminates these variables. The setup does not need to be expensive. A fixed tripod position, two diffused LED panels, and an opaque shroud to block ambient light produces consistent, colour-accurate images across every tray, every day.
Including a colour reference chart (such as a Calibrite ColorChecker Classic or a colour strip) in every frame allows post-processing to correct for any remaining colour shift. This is not perfectionism: it is the minimum standard required for meaningful colour comparison across trays photographed at different times.
3. Capture the full tray, including all metadata
Every photograph should include the entire tray with visible hole ID, tray number, from-depth, and to-depth markings. Cropping out tray edges or metadata blocks makes the photograph harder to catalogue, harder to match to the logging database, and useless for automated systems that rely on optical character recognition (OCR) to extract depth and hole identification.
One tray per image. Full coverage. No cropping. The five seconds saved by a hasty, off-centre shot costs hours of manual reconciliation later.
4. Use a consistent file naming convention tied to the database
A naming format like HoleID_TrayNumber_FromDepth_ToDepth (for example, DDH001_015_45.00_50.30) links the photograph directly to the logging database without manual matching. Adding a suffix for wet or dry state (_W or _D) preserves that context in the filename rather than relying on memory or an external log.
Inconsistent or generic filenames (IMG_4532.jpg, Photo_Tuesday_afternoon.jpg) create a reconciliation problem that scales with every tray photographed. On a 200-hole programme, that is thousands of images requiring individual verification. The naming convention should be established before the first tray is photographed and enforced consistently through the campaign.
5. Standardise core preparation before every shot
Consistent preparation turns a photograph from a snapshot into a calibrated technical record. The standards are straightforward:
Align orientation lines with the bottom of the tray channel so they are visible but not obscuring rock surfaces. Open joints slightly (approximately 0.5 centimetres) so fracture edges are photographed clearly. Mark drillers' breaks with a visible X within 5 centimetres of each mechanical break so they are not confused with natural fractures in later review. Use consistent marker colours throughout the programme: white or black for metre marks, red for sample boundaries, yellow for lithological contacts. Minimise additional writing on the core to avoid obscuring textures.
The preparation takes minutes per tray. It is the difference between a photograph that records the geology and one that merely records the appearance of a tray.
The bottom line
The core gets cut. The photo is the only record that survives whole.
Core photography is not a task to delegate to the least experienced person on the crew. It is a geological documentation exercise that produces a permanent, auditable record of the programme's physical material. The five habits above cost almost nothing in additional time or equipment, and they produce a photographic archive that is usable for re-logging, machine learning, audit review, and investor presentation years after the drill rig has moved on.
At Norwest Exploration and Mining Services, we deploy geologists and field technicians who treat core documentation as a professional standard. If your programme needs people who understand that data quality starts at the tray, reach out directly or visit our profile.