Mineral resource and reserve definitions

Resources and Reserves Definition

Mineral Deposit/Deposit

mineral deposit/deposit is zone that has concentration of minerals of economic interest. There is confirmation of geological occurrence, continuity with approximation of tonnage and grade. However the data are insufficient to classify it as a resource.

Resources/Mineral Resources

resource is a zone that has concentration of minerals of economic values that are sampled and studied to an extent where a credible estimation of the tonnage and grade can be made.
The resources are divided into three categories depending on the level of economic confidence and certainty of geologic existence. The three different categories of mineral resources:

1. Inferred Resources


Inferred resource is part of a mineral resource where the tonnage and grade can be estimate with low level of confidence and certainty. It is based on information garthered through appropriate techniques form location such as outcrops, trenches, pits, workings and widely spaced (>100m) drill holes which may be of limited or uncertain quality and reliability. 
It has  relatively low level of geological knowledge of its occurrence and low level of confidence in its economic feasibility.

2. Indicate Resources

Part of a mineral resource that have been sampled (from locations such as outcrops, trenches, pits and drill holes) to a point where an estimate has been made, at a reasonable level of confidence and certainty, of their contained metal, grade, tonnage, shape, densities, and the physical characteristics and usually serve as a basis for mine planning.
It has  moderate level of geological knowledge of its occurrence and low level of confidence in its economic feasibility.

3. Measured Resources

Part of a mineral resource that have undergone enough further sampling that a 'competent person' (defined by the norms of the relevant mining code; usually a geologist) has declared them to be an acceptable estimate, at a high degree of confidence and certainty, of the grade, tonnage, shape, densities, physical characteristics and mineral content of the mineral occurrence.
It has  very of geological knowledge of its occurrence and low level of confidence in its economic feasibility.

The graphical illustration below summarizes the concept in more readable and easily interpreted manner. The confidence level of a resource/reserve economic feasibility increases from the left to the right while the knowledge of geological existence increases from top to bottom.

The JORC (Joint Ore Reserve Committee Codes)

Reserves / Ore Reserves


Ore reserves are resources known to be economically feasible for extraction. Reserves are either probable or proven reserves.

1. Probable reserve

probable ore reserve is the part of indicated resources that can be mined economically. It includes factors like dilution, recovery, and commodity price. It is of sufficient quality to serve as the basis for decision on the development of deposit.

It has  relatively moderate to high level of geological knowledge of its occurrence and high level of confidence in its economic feasibility.

2. Proven reserve 

proven ore reserve is the part of measured resources that can be mined in an economically viable fashion. It includes diluting materials and allowances for recovery and the commodity price. A proven ore reserve represents the highest confidence category of reserve estimate.

It has  very high level of geological knowledge of its occurrence and high level of confidence in its economic feasibility.
...........
In summary, the class that a resource or reserve fall is dependent on the level of confidence of its economic feasibility and the geological knowledge available at the time of determination. They are convertible between the different categories depending on the two principal factors:
- Geologic Knowledge
- Economic Feasibility

For example:

The downturn in commodity prices in the recent years inflicted bulk of the proven ore reserve to be converted to measured resources. Even though, the knowledge of geologic existence remains  high, the confidence of economic feasibility drops. The cut-off-grades has to be raised in response to the prevailing economic climate causing those below the cut off grade uneconomical and consequently converted to measured resources. 


Mineral resource and reserve definitions Mineral resource and reserve definitions Reviewed by CEDRICK KAU on March 09, 2016 Rating: 5

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