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3 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 · 20 min read
Mining · 19 August 2026
Nine Grams a Tonne
What does it actually cost to pull an ounce of gold out of the ground? The honest answer runs through grade decline, energy and water bills, permitting delays and the closure liabilities nobody prices…
Amara Okonjo · 18 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 · 15 min read
