Modifying factors are the set of mining, metallurgical, infrastructure, economic, marketing, legal, environmental, social, and governmental considerations that must be applied to a mineral resource estimate in order to convert it into a mineral reserve under internationally recognized reporting codes such as JORC, NI 43-101, or SAMREC. While a mineral resource describes the in-situ quantity and quality of mineralization based on geological data, a mineral reserve represents the economically and technically mineable portion after accounting for these realistic modifying factors. Mining modifying factors address achievable extraction methods and dilution; metallurgical factors consider expected recovery rates during processing; infrastructure factors assess access to power, water, transport, and processing facilities; economic and marketing factors evaluate commodity price assumptions and the existence of viable sales markets; and legal, environmental, social, and governmental factors confirm that necessary permits, community agreements, and regulatory approvals are reasonably expected to be obtained. For bauxite and iron ore projects, infrastructure modifying factors such as port and rail access are often decisive, while for gold and diamond projects, metallurgical recovery and marketing arrangements for the final product carry particular weight. Competent persons must justify each modifying factor applied in public reserve disclosures.
