Basic concepts in three-part quantitative assessments of undiscovered mineral resources

Abstract

Since 1975, mineral resource assessments have been made for over 27 areas covering 5 x 10" km 2 at various scales using what is now called the three-part form of quantitative assessment. In these assessments, (1) areas are delineated according to the types of deposits permitted by the geology, (2) the amount of metal and some ore characteristics are estimated using grade and tonnage models, and (3) the number of undiscovered deposits of each type is estimated.Permissive boundaries are drawn for one or more deposit types such that the probability of a deposit lying outside the boundary is negligible, that is, less than 1 in 100,000 to 1,000,000.Grade and tonnage models combined with estimates of the number of deposits are the fundamental means of translating geologists" resource assessments into a language that economists can use.Estimates of the number of deposits explicitly represent the probability (or degree of belief) that some fixed but unknown number of undiscovered deposits exist in the delineated tracts. Estimates are by deposit type and must be consistent with the grade and tonnage model. Other guidelines for these estimates include (1) frequency of deposits from well-explored areas, (2) local deposit extrapolations, (3) counting and assigning probabilities to anomalies and occurrences, (4) process constraints, (5) relative frequencies of related deposit types, and (6) area spatial limits. In most cases, estimates are made subjectively, as they are in meteorology, gambling, and geologic interpretations.In three-part assessments, the estimates are internally consist.ent because delineated tracts are consistent with descriptive models, grade and tonnage models are consistent with descriptive models, as well as with known deposits in the area, and estimates of number of deposits are consistent with grade and tonnage models. All available information is used in the assessment, and uncertainty is explicitly represented.

Aggregation of estimated numbers of undiscovered deposits: an R-script with an example from the Chu Sarysu Basin, Kazakhtan: Chapter B in <i>Global mineral resource assessment</i>

“…The probable amounts of mineral resources associated with undiscovered deposits by deposit type may be estimated by combining a probability distribution for the number of undiscovered deposits of a given type within a tract with appropriate grade and tonnage distributions in a Monte Carlo simulation (Root and others, 1992;Singer, 1993;Singer and Menzie, 2010).…”

A Framework for Quantitative Assessment of Impacts Related to Energy and Mineral Resource Development

“…The resource quantity estimate, along with the input data, is also suitable for incorporation with diverse datasets as described below. Singer and Menzie (2010) and Singer (1993) describe an assessment method (Fig. 1b) for mineral resources.…”

The Global Mineral Resource Assessment Project

“…2). Three-part assessments consist of the following (Singer, 1993): 1. Delineating areas permissive for undiscovered mineral resources according to the types of deposits permitted by the geology 2.…”