Resource reporting is where most of the confusion in junior mining investing lives. The categories are not interchangeable: an inferred resource rests on limited drilling and cannot legally be converted straight into a reserve, while a proven reserve has survived an economic study. Two companies can quote similar ounce counts and mean very different things by them.
The terms below cover the classification ladder, the study stages that move a project up it, and the equivalence measures — copper equivalent, silver ounce equivalent, total rare earth oxides — that let polymetallic deposits be quoted as a single number. Read the definitions alongside the actual disclosure, because the categories are defined by confidence, not by size.
14 terms in this section.
A conversion metric used to express the combined value of multiple metals in polymetallic deposits as equivalent copper. CuEq calculations include copper content plus the value of by-products (gold, silver, molybdenum) converted to equivalent copper at specified metal prices.
A comprehensive technical and economic study of a mineral project used to demonstrate whether the project is economically viable and technically feasible. Feasibility studies are required before a project can proceed to development and must be prepared by qualified persons under NI 43-101 standards.
A mineral resource for which quantity, grade, densities, shape, and physical characteristics are estimated with sufficient confidence to allow the appropriate application of technical and economic parameters. Indicated resources have a higher level of confidence than inferred resources but lower than measured resources.
A mineral resource for which quantity and grade are estimated based on limited geological evidence and sampling. Inferred resources have the lowest level of geological confidence and should not be converted to mineral reserves. Further exploration is required to upgrade to indicated or measured categories.
A mineral resource for which quantity, grade, densities, shape, and physical characteristics are estimated with confidence sufficient for the appropriate application of technical and economic parameters to support production planning. This is the highest level of geological confidence in resource estimation.
The economically mineable portion of a measured or indicated mineral resource, demonstrated by at least a preliminary feasibility study. Mineral reserves include consideration of mining, metallurgical, economic, marketing, legal, and environmental factors.
A concentration of material of economic interest in or on the Earth's crust in such form, grade, and quantity that there are reasonable prospects for economic extraction. Resources are classified as measured, indicated, or inferred based on confidence level.
The standard unit of measurement for precious metals, equal to 31.1035 grams. Gold, silver, platinum, and palladium are typically quoted and traded in troy ounces. Not to be confused with the avoirdupois ounce (28.35 grams) used for everyday items.
An initial economic analysis of a mineral project that includes estimates of capital and operating costs, metal prices, and project economics. PEAs are less detailed than feasibility studies and carry higher uncertainty, but help determine if a project warrants further study.
The economically mineable portion of an indicated and, in some cases, a measured mineral resource. Probable reserves have a lower level of confidence than proven reserves but are still suitable for mine planning purposes.
The economically mineable portion of a measured mineral resource, representing the highest level of confidence in reserve estimation. Proven reserves are suitable for detailed mine planning and financing decisions.
The concentration of silver in ore, measured in grams per tonne (g/t) or ounces per ton (oz/t). Primary silver deposits typically range from 100-500 g/t Ag, while by-product silver from base metal deposits is often 10-50 g/t. High-grade silver veins can exceed 1,000 g/t.
A conversion metric used to express the value of polymetallic deposits in terms of silver ounces. AgEq calculations include silver content plus the value of other metals (gold, lead, zinc) converted to equivalent silver ounces at specified metal prices.
The sum of all rare earth element oxides in a mineral deposit, typically expressed as a grade percentage or parts per million (ppm). TREO is the standard metric for reporting rare earth resource estimates and provides a measure of total rare earth content.