Mineral reserves are classified based on the level of geological knowledge, confidence, and economic feasibility of mining the minerals. The classification system divides mineral deposits primarily into Mineral Resources and Mineral Reserves, each with specific subcategories:
Mineral Resources are concentrations of minerals with economic interest in the Earth’s crust and are classified into three categories by increasing geological confidence:
- Inferred mineral resource: they are estimated with low confidence based on limited geological evidence, involving uncertainty.
- Indicated mineral resource: those are estimated with reasonable confidence based on more detailed sampling and geological data.
- Measured mineral resource: estimated with high confidence and verified by a competent person with thorough sampling and analysis.
Mineral Reserves are the economically mineable parts of Measured and/or Indicated Mineral Resources and are subdivided by confidence and economic viability:
- Probable mineral reserve: the economically mineable part of an indicated resource (and sometimes Measured), with moderate confidence, accounting for dilution, losses, and other modifying factors.
- Proved (or proven) mineral reserve: the economically mineable part of a measured resource, representing the highest confidence category with thorough evaluation of geological and modifying factors.
This classification framework is widely recognized internationally through standards such as the CRIRSCO International Reporting Template, JORC, PERC, CIM, and SAMREC codes. It is fundamental for assessing project viability, guiding investment decisions, and planning mining operations.
