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2 results for “fire assay” 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
A significant share of the world's gold is produced by people working with hand tools, informal finance and a neurotoxin. Formalisation is the stated solution. Nobody agrees on what it costs. · Artisa…
Amara Okonjo · 12 min read
