A neat core tray shows what a drilling team recovered. It can leave the missing material almost invisible. When the material lost during drilling differs from the material retained, the surviving sample may give a distorted picture. The owner's decision is whether recovery problems require a different technique, further investigation or a limit on interpretation.
Record absence with the same care as presence
The drilling record should identify recovery by interval and preserve observations about broken, soft or washed material. Photographs, driller notes and geological logs help explain what happened. A single average for the whole hole can conceal a problematic interval at the boundary of an important zone. JORC's checklist asks about drill-sample recovery and possible relationships between recovery and grade. Those questions should be addressed while the crew can still reconstruct field conditions, rather than after a model reviewer discovers unexplained gaps in the database.
Look for a directional problem
Low recovery does not automatically make every assay unusable. The investigation needs to consider whether the lost material could systematically differ in mineral content or physical properties. In a hypothetical weathered interval, fragile material might be more difficult to retain than competent rock. The team should test the actual conditions instead of assuming which fraction carries value. Comparing recovery, geology and assays can reveal patterns that deserve follow-up. An attractive result remains an observation of recovered material until its representativity has been adequately examined.
Change the programme where evidence requires it
The owner can ask the drilling and geological specialists to propose practical alternatives, with the information each would provide. Changes might involve equipment, drilling practice, sample handling or confirmatory investigation, depending on the deposit. The decision should reflect the reason for the loss. Ordering more holes using the same problematic approach may multiply uncertain data. CIM's database guidance supports evaluating information for its intended use. The relevant acceptance criterion is enough reliable evidence to support the interpretation being made, with limitations recorded for later users.
Preserve the consequence in public language
A reviewer should be able to see whether problematic intervals were excluded, treated cautiously or investigated further. Those choices should reconcile with the model and with any public summary. Replacing a missing interval with an unexplained assumption hides the very uncertainty investors need to assess. The commercial benefit of disciplined recovery records is a better basis for choosing the next investigation and a clearer explanation of what remains unknown. Reporting the gap honestly can prevent a technical weakness from becoming embedded in mine planning, processing assumptions and a financing narrative that depends on representative feed.
