Evaluation of Mineral Reserves

The following job refers generally to the evaluation, through conventional methods of the inventory of minerals of metallic deposits of subterraneous exploitation that includes auriferous mining.

It is considered that the criteria and procedures are general and not permanent having to be updated according to the advances in technology.

Classification of Minerals

Type of mineral according to certainty

Proven
Is one in which there is virtually no risk of discontinuity between tested faces.

Probable
In one in which the risk factor is greater than the indicated for the proven mineral, but that has enough geological evidences to suppose the continuity of the mineral.

Prospective
Is that in which the risk factor is higher that the indicated for the proven mineral, but that has enough geological evidences to suppose the continuity of the mineral.

Potential
Is an estimation that is based mainly in the broad knowledge of geological character of the deposit, its exposition depends on direct indications.

Types of minerals according to their accessibility

Accessible
Are those that are intercepted by mining labor and that are generally ready to enter the stage of preparation. They are considered reserves when their value is above the total cost of operation.

Eventually Accessible (Partially Accessible)
Are those that are not expedited for their immediate exploitation since they are made up of blocks that are not accessible. These minerals make up reserves if the costs of development for making them accessible are under the total normal costs of operation. 

Inaccessible
Are those whose special position is similar to the indicated for those that are eventually accessible. These minerals are the ones in which the amount of the investment for them to be accessible plus the total cost of a normal operation, is not covered by the value of those minerals and therefore they do not constitute reserves.

Types of minerals according to their Value

Mineral Reserves
These are the economic minerals or those that are commercially accepted in the market under the effective conditions. In this category are the proven and probable, accessible and or eventually accessible and economically exploitable.

Marginal Mineral
Are all those that cover the direct expenses and part of the indirect expenses, not in totality the paying offs, depreciations and financial expenses. This mineral is a potential because with a reduction of costs or the increase of prices of the metals can turn into mineral reserves.

Submarginal Mineral
Are all those that do not cover the indict expenses under the existing conditions and under even better conditions they will not be enough to totally cover the indirect costs.