A mineral inventory is a comprehensive quantitative and qualitative accounting of all mineral resources and mineral reserves identified within a mining project or operating mine, expressed in terms of tonnage, grade, classification, and confidence category in accordance with a recognized international reporting standard. The mineral inventory forms the foundational dataset upon which all mine planning, project valuation, and investment decisions are based. It is compiled from borehole databases, geological models, geostatistical estimation outputs, and modifying factors including economic parameters, mining constraints, and metallurgical recovery data. Under the JORC Code (used in Australia and widely internationally), the NI 43-101 standard (Canada), or the SAMREC Code (South Africa), mineral inventories are classified into Measured, Indicated, and Inferred Mineral Resources, and Proved and Probable Mineral Reserves, each reflecting a different level of geological confidence and economic viability. In iron ore and bauxite mining, the mineral inventory quantifies total ore tonnes, average iron or aluminum grades, strip ratios, and impurity levels (silica, alumina, phosphorus). In gold mining, the inventory specifies total gold ounces in situ at defined cut-off grades. Diamond inventories include estimated carats per tonne and total carat content. The mineral inventory must be maintained, updated, and reconciled against actual production data throughout the life of the mine to reflect changes in geological knowledge, commodity prices, mining costs, and reserve depletion.
