A Mineral Resource is a concentration of minerals in the Earth’s crust or surface with reasonable prospects for eventual economic extraction. It is identified and estimated through geological evidence, sampling, and testing. It is not yet proven to be economically mineable. E.g., What’s there geologically?

Subcategories (increasing confidence):

  • Inferred Resource → lowest confidence, based on limited data.
  • Indicated Resource → more sampling, better confidence.
  • Measured Resource → highest confidence in geology and grade continuity.

Think of a resource as “what we know is in the ground or surface.”

A Mineral Reserve is the economically mineable portion of a measured or indicated resource.

A mineral resource is then modified after applying the practical aspects required for commercialization: mining technology, mineral processing, economic, legal, environmental, and social considerations. Feasibility studies showing profitability provide the detailed data.

Subcategories (increasing confidence):

  • Probable Reserve → based on Indicated (and sometimes Measured) Resources.
  • Proven Reserve → highest confidence, based on Measured Resources and full economic feasibility.

A reserve is “what we can mine economically today.” E.g., What’s there AND profitable to extract (economically and legally).

There are legal classifications based on the Committee for Mineral Reserves International Reporting Standards (CRIRSCO family) of standards used by mining companies to report to retail investors on a stock market, including, but not all:

  • Joint Ore Reserves Committee (JORC) from Australia
  • National Instrument (NI 43-101) from Canada
  • South African Code for the Reporting of Exploration Results, Mineral Resources and Mineral Reserves (SAMREC) from South Africa
  • Pan European Reserves and Resources Reporting Committee (PERC) for Europe
  • Securities and Exchange Commission (SEC S-K 1300) for the United States
  • Etc.

So when a mineral reserve is ‘Proven’, we have a very high degree of confidence that the amount of minerals exists and it is both economically and legally practical to mine.