An assay result underpins every exploration decision: continue, drill, estimate or walk away. QA/QC (quality assurance and quality control) covers the procedures that show those results are accurate, precise and free of contamination.
Three control tools
- Standards (certified reference materials) have a known grade. They measure laboratory accuracy.
- Blanks contain none of the target metal. They detect contamination during preparation or analysis.
- Duplicates (field, coarse reject, pulp) measure precision and sampling representativeness at each stage.
These control samples are inserted blind into the sample stream: the laboratory does not know which samples are controls. Their insertion rate is set at the start of the programme.
Chain of custody
Every sample must be traceable from the field to the laboratory: unique numbering, dispatch sheets, sealed packaging, documented transport. Without chain of custody, even an excellent result can be challenged.
External checks
A share of the pulps is regularly sent to a second, independent laboratory. This external check can reveal systematic bias that internal controls would miss.
What happens without QA/QC
Unchecked data can be ruled unusable during an audit or due diligence. Samples then have to be re-assayed, or holes re-drilled, at the cost of months of delay and extra budget. A clean, documented database, on the other hand, reassures partners and speeds up every later stage.
Our practice
We define the QA/QC protocol before the first sample, track the controls batch by batch with control charts, and document every failure and every corrective action. The result: data you can show to any auditor.
