The Lasky cumulative tonnage-grade relationship; a reexamination

The need for interdisciplinary research on resource appraisal techniques was recognized by Samuel G. Lasky, a U.S. Geological Survey geologist, more than 30 years ago. His efforts to devise an appraisal technique that incorporated many attributes of mineral resources resulted in a cumulative tonnage-grade relationship that has been referred to as "the arithmetic-geometric (A/G) ratio" or "Lasky's law" by later writers. A review of subsequent studies of the increases in available metal to be expected as grade decreases indicates that Lasky's work has at times been misinterpreted. Lasky's relationship is shown to be consistent with studies of the correlation between average grades and tonnages of mineralized material in ore deposits. The projection of Lasky's analysis to lower grades is limited because the mathematical formulation predicts physically impossible situations below some limiting grade.