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2 results for “assay office hallmark” in Mining
Mining · 5 August 2026
Grade, Cut-off and the Arithmetic of an Open Pit
…per tonne is one part per million — the metal is invisible in the rock and is detected by assay, not by eye. · What is cut-off grade? The lowest grade at which a tonne of rock generates more revenue than it costs to process. Rock above it is ore and goes to the mill; rock below i…
Amara Okonjo · 16 min read
Mining · 22 May 2026
The Other Supply Chain: Artisanal Mining and the Mercury Problem
…but because the form does not describe him. · They tell us to become legal. I went to the office three times. Each time it was a different list. Meanwhile the buyer at the road pays cash today and asks nothing. Miner, West Africa · Where formalisation has worked, it has generally…
Amara Okonjo · 12 min read
