In the mining industry, the terms “mineral resources” and “mineral reserves” are often used as though they mean the same thing. However, they refer to two very different realities. Understanding this distinction is essential for evaluating the true value of a mining project, its stage of development, and its economic potential.
Misinterpreting these concepts can lead to significant errors when assessing a project, both for investors and mining companies. Behind these terms are complex geological analyses, rigorous technical studies, and major economic considerations.
Before a mine can enter production, a deposit must go through several stages of evaluation. Resources represent the geological potential identified in the ground. Reserves, on the other hand, refer to the economically mineable portion of those resources under current technical, environmental, and financial conditions.
Understanding this difference helps better assess the risk associated with a mining project and better interpret the technical reports produced within the industry.
What is a mineral resource?
A mineral resource is a natural concentration of minerals in the ground whose existence has been demonstrated through geological exploration work.
These resources are identified using different methods such as geological surveys, geochemical analyses, geophysical surveys, exploration drilling, sampling, and 3D geological modeling.
At this stage, geologists mainly evaluate the presence of the ore, its volume, grade, and continuity within the deposit.
However, a mineral resource does not guarantee that mining operations will be profitable. It simply indicates that a mineral potential exists with a certain level of geological confidence.
Resources are generally divided into three categories.
Inferred resources
This is the lowest level of confidence. Available data is limited and the geological interpretation remains partial.
These resources are often used to guide future exploration work, but they are not sufficient for making major economic decisions.
Indicated resources
The confidence level is higher. Exploration work provides a better understanding of the geometry and grade distribution of the deposit.
This category already allows for certain preliminary economic studies to be carried out.
Measured resources
This is the highest level of geological confidence for a mineral resource. The available data is extensive and precise enough to support advanced technical analyses.
Measured resources often form the basis for future mineral reserves.
What is a mineral reserve?
A mineral reserve is the economically mineable portion of a mineral resource.
In other words, even if a deposit contains ore, it only becomes a reserve when it can be extracted profitably under current conditions.
To convert resources into reserves, several factors must be analyzed, including mining methods, production costs, metal prices, available infrastructure, environmental constraints, geotechnical considerations, regulatory requirements, and operational risks.
Mineral reserves therefore rely on studies that are far more advanced than basic exploration work.
There are two main reserve categories.
Probable reserves
Probable reserves generally come from indicated resources and sometimes measured resources. The confidence level is high, although some economic or technical uncertainties may still remain.
Proven reserves
Proven reserves represent the highest level of confidence. They are based on highly detailed data and comprehensive technical studies.
These reserves usually support final investment decisions and mine development planning.
An essential distinction when evaluating a mining project
In mining, resources and reserves do not represent the same level of certainty or profitability.
Resources indicate the potential presence of a mineral deposit, while reserves demonstrate that profitable extraction is feasible under specific conditions.
This distinction is central to any serious mining project evaluation. It helps better understand the risks, opportunities, and actual potential of a project.
Estimating resources and reserves requires advanced technical expertise, a rigorous understanding of industry standards, and a comprehensive view of economic, geological, and environmental factors.
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