What this place is
The Super Pit swallowed a century of small underground workings on the Golden Mile into a single hole 3.5 km long. It is the most photographed mine in Australia.
Grade. Low grade by underground standards, made economic by scale.
“Grade” is the percentage of the useful stuff in the rock. A copper mine at 0.5% grade throws away 199 tonnes of rock for every tonne of copper it sells. That single number decides whether an orebody is a mine or just an interesting piece of geology.
What comes out
Gold
The metal that does not tarnish, does not corrode and never runs out once mined — which is why almost all of it ever…
Silver
The best electrical conductor there is, and the metal that has been used as money for longer than almost anything…
A “by-product” is a metal recovered because it happens to be in the same rock, not because anyone went looking for it. Its supply therefore follows the primary metal’s economics, not its own.