Ore grade

Ore grade is the concentration of a valuable mineral or element in material mined or considered for mining. It is commonly reported as a percentage, parts per million, or mass per tonne.

Mineral resource estimation: The process of estimating the quantity, grade, and geological confidence of mineral resources from exploration data. Assay results and geological models combine to estimate how grade varies through a deposit.
Open-pit mining: A mining method that extracts deposits from a surface excavation with progressively deeper benches. Ore grade helps determine which benches and blocks justify extraction.
Ore reserve: The economically mineable portion of a mineral resource, established through modifying factors and appropriate technical studies. A high grade alone does not make material a reserve without demonstrated economic mineability.
Mineral deposit: A natural concentration of minerals in Earth's crust that may be of geological or economic interest. Grade describes the concentration of valuable material within a deposit.
Fire assay: A laboratory method that measures precious metals by concentrating them into a lead button and analyzing the resulting bead. It provides precise gold and silver grade measurements in many ore samples.
Underground mining: The extraction of mineral deposits through shafts, tunnels, and other workings beneath the surface. Higher operating costs often make grade especially influential in underground mine planning.
Head grade: The concentration of a valuable material in feed entering a processing plant. It is a specific operational grade measured after mining and before processing.
Ore: Rock or sediment containing valuable material that can be extracted and processed economically under specified conditions. Ore grade helps distinguish valuable concentrations from surrounding material, though economics also matter.
Inductively coupled plasma mass spectrometry: An analytical technique that identifies and quantifies elements by measuring ions in a plasma with a mass spectrometer. It can determine trace-element grades from prepared ore samples.
Heap leaching: A process that recovers metals by applying a leaching solution to stacked, crushed or run-of-mine ore. Low-grade ores can be treated this way when their metal is sufficiently recoverable.

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