A way of expressing a polymetallic deposit as though it were all copper, using relative metal prices.
A conversion metric used to express the combined value of multiple metals in polymetallic deposits as equivalent copper. CuEq calculations include copper content plus the value of by-products (gold, silver, molybdenum) converted to equivalent copper at specified metal prices.
Equivalence lets a deposit carrying copper, gold and silver be quoted as one number. It is useful for comparison and easy to flatter, because the result depends entirely on the prices and recoveries chosen.
Equivalent grades assume every metal is recovered and paid for. If the by-product does not report to concentrate, or is penalised by the smelter, the equivalent number overstates what is actually saleable.