The upgraded product a mine ships — ore reduced to a fraction of its bulk with most of the metal retained.
The product of mineral processing that contains elevated concentrations of valuable metals. Concentrates are typically shipped to smelters for final metal recovery. For example, a copper concentrate might contain 25-30% copper.
Selling concentrate rather than metal means a third party sets much of your economics. Treatment and refining charges, payable percentages and impurity penalties are all negotiated, and none of them appear in a headline grade.