Grade the amount of valuable mineral in each ton of ore, expressed as troy ounces per ton for precious metals and as a percentage for other metals. Cut-off grade is the minimum metal grade at which an ore body can be economically mined. Millhead grade is metal content of mined ore going into a mill for processing. Usually lower than reserve grade because of dilution. Recovered grade is actual metal content of ore determined after processing.
Reserve grade is estimated metal content of an ore body, based on reserve calculations.
The gold-laden solution is collected for gold recovery. Infill drilling drilling within a group of previously drilled holes to provide a closer spaced pattern to define more accurately the parameters of the ore body. Layback the amount of material which must be mined for the slope of a pit wall to be at a safe angle. The broken rock is extracted and the resulting open chamber is not filled with supporting material. Mill a plant where ore is ground fine and undergoes physical or chemical treatment to extract the valuable metals.