Low Grade

Ore within a mine which has a much lower gold content than the average run of the mine. Low grade ore may be mined as part of an orebody when it is not below the economic cut-off grade and is usually blended with higher grade ore to produce an average grade. Low grade mineralization may also be mined, if practical, if it becomes economic, such as in periods when the gold price is high or when new technology is introduced. Orebodies, notably in the United States and Western Australia, which have a very low gold content of one gram per tonne or less, can now be mined by heap leaching and carbon-in-pulp recovery. Such new technology has made payable many deposits that were previously considered uneconomic. See also Grade.