Core Photography, Storage and Records

Core photography, storage and records preserve different parts of an investigation. Photographs capture visible condition at a particular time; physical storage retains material for inspection or testing; records connect that evidence to its location, sampling and history. Their value depends on maintaining those relationships. A well-lit image without a reliable hole and depth identity is not a usable substitute for a traceable sample.^[1]

Preservation also has limits. Material can be consumed, disturbed or altered after recovery. An archive should explain what remains and how it has changed, rather than imply that an old sample necessarily retains every property it had in the ground.^[2]

Establishing Identity Before Photography

The photographic record starts with verified material identity. Hole and box identifiers, run boundaries, depth labels, core sequence and marked gaps should agree with the drilling and logging records. Samples removed earlier should be identifiable so that an empty space is not mistaken for drilling loss.^[3]

CIM's exploration guidance recommends photography before splitting or sampling core. The purpose is to retain evidence of the material before an irreversible change. Subsequent images can document sampling or re-logging, but their dates and relationship to the original condition need to remain clear.^[1]

A useful record distinguishes the box’s depth interval from the exact positions of uncertain fragments or missing material. Neat arrangement must not manufacture continuity. Depth-order arrows and matching marks are also not necessarily in-situ rotational references: their meaning must be recorded before an image is used for structural interpretation. Unresolved depth discrepancies should remain visible in the image metadata.^[4][3]

Making Images Comparable

Consistent lighting, viewing geometry, focus and scale improve comparisons between images. Labels and reference scales need to be legible, and detail images should remain linked to the overview and sample interval. Shadows, glare and perspective can otherwise be mistaken for changes in colour, texture or feature dimensions.^[4]

The USGS method for its Idaho National Laboratory archive describes controlled core-box positioning, legible hole and depth identification, and documented capture and post-processing. This is an archive-specific example of comparability and traceability, not a requirement to use identical equipment at every mine. Controlled photography does not itself establish mineral identity or provide an analytical grade.^[4]

Surface condition should be recorded. Wet and dry appearances may differ, and cutting or cleaning can change what is visible. Reclamation describes wet and dry photography for core logging, while its preservation guidance recognises material damaged by changes in moisture. Consequently, a photographic treatment should not compromise a sample needed for another investigation; suitability depends on the material and intended tests.^[3][2]

Images support interpretation but have boundaries. They record the visible surface, not every internal feature or the full condition of a discontinuity. Colour changes cannot automatically be read as changes in mineral composition without controlling imaging conditions and checking the material. A photograph also cannot replace the physical specimen for a test requiring mass, volume, strength or chemical analysis.

Originals, Derivatives and Metadata

Original captures should be retained separately from cropped, corrected or annotated versions. A processing record should identify adjustments and preserve the link to the original file. The USGS workflow retains original image files alongside processed outputs; this enables later review of what was captured and what was subsequently changed.^[4]

Metadata should connect the image to the project, hole, box or interval, date, photographer and material condition. For a close-up, an additional link to its location within the box prevents the image becoming detached from its geological context. Names and directories help discovery, but a stable identifier is more reliable than a description that may change during interpretation.

Annotations should remain recognisable as interpretation. Drawing a contact or labelling a mineral on an image does not turn that interpretation into a direct measurement. Keeping annotations separate or retaining an unannotated original makes later reassessment possible without erasing the historical interpretation.

Physical Storage and Material Suitability

Storage arrangements should protect both the specimens and their identity while allowing practical retrieval. Reclamation's guidance identifies protection from damage and unauthorised access, readable identification, inventory records and accessibility as important features of core storage. Its recommendations were developed for water-infrastructure investigations; project-specific retention obligations require their own review.^[2]

Preservation should respond to material behaviour and proposed use. Slaking or moisture-sensitive material may deteriorate during storage, while some specialised samples need preparation and protection beyond ordinary core-box storage. A specimen that remains useful for lithological identification may no longer be suitable for a test intended to represent its original physical condition.^[2]

Archive condition therefore needs assessment before reuse. A later researcher should be able to determine whether the material is whole, split, sampled, weathered or otherwise modified. Recording an observed change is preferable to assuming that a present-day inspection reproduces the original investigation conditions.

Storage location is part of the evidence chain. A sample record should lead to an identifiable container and location, and transfers should update the inventory. Physical survival without retrievability can make an archive practically unusable even when the original photographs remain accessible.

Sampling, Loans and Custody

Removing material creates a new record relationship. The parent hole and interval should connect to the subsample, destination, test, remaining material and resulting report. Later sampling must be distinguished from original drilling loss, including where a laboratory specimen is destroyed. Coordinating petrography, chemical analysis and other tests helps avoid consuming evidence still needed by another discipline.^[1][3]

The British Geological Survey's National Geological Repository provides an institutional example: its sampling arrangements use individual barcodes so that derived samples can be traced in later reports. That illustrates traceability, rather than imposing the repository's own access or sampling conditions on all exploration programmes.^[5]

Retention and disposal decisions should account for future technical needs, ownership, agreements and applicable requirements. No single storage duration follows from the fact that material is drill core. Before an authorised disposal or transfer, the project needs a clear inventory and a record of what evidence will no longer be available.^[1]

Digital Preservation and Future Use

Digital preservation needs more than a folder of images. Logs, surveys, sample registers, analytical results and metadata should remain linked, with responsibility for maintaining the archive. The USGS data-management guidance recommends retaining metadata with data, independent backup locations and checks that backed-up files can actually be recovered and opened.^[6]

Checksums can detect changes relative to a recorded file version; an intentional edit also changes the checksum and needs a new version record. Matching checksums do not validate the original labels or geological interpretation. Likewise, a recoverable backup does not correct a missing sample identifier. File integrity, recoverability and scientific validity are separate checks.^[6]

A final handover should allow another user to reconstruct the evidence: where the material came from, its condition when photographed, what was removed, how descriptions changed and where retained specimens and digital records can be found. This makes preservation an active part of the investigation rather than a final housekeeping task. It also makes later limitations explicit, so that future testing or re-interpretation begins with the evidence that actually survives.