Oxidation is not weathering and the distinction matters for mine waste classification. Our WA Practice Lead Andrew Botfield has written a short explainer for study managers, project geologists and mine planners scoping characterisation programs on early-stage projects. (See https://lnkd.in/p/gqaPivUe)

The key message is that an oxide zone is defined by weathering, not oxidation. The two commonly occur together, but they are not necessarily coupled.

Reduced sulphur can persist within weathered profiles, and where it does, position in the profile is not a reliable indicator of material behaviour. Potentially acid-forming (PAF) material can then be misclassified, and even relatively small volumes can become significant liabilities towards mine closure.

Where the two processes part company, transitional material can carry an elevated Acid and Metalliferous Drainage (AMD) risk, and programs should be designed around materials rather than tonnage.