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Definitions |
1 Consulting Geologist, 73 Roxburgh Road, London SE27 0LE, UK
2 Mineral Economy and Energy Research Centre, Polish Academy of Sciences, U1. Wybickiego 7, 31-261 Krakow, Poland
Classification of reserves in the former Comecon countries is based on two reference axes: the abscissa represents the degree of reserve identification and the ordinate shows the possibility of economic utilization. Accordingly, reserves are classified as documented and prospective and as economic and uneconomic.
Documented reserves are divided into categories A, B, C1 and C2. The first two of these categories relate only to developed and blocked reserves, with category A being in practical terms restricted to reserves under advanced exploitation, often at a stage nearing exhaustion. Category C1 comprises reserves which have been identified and examined to such an extent as to enable a positive definition of their suitability for exploitation; these reserves are often in early production phases. Category C2 relates to reserves which have been identified and documented at a preliminary stage only. Terminology of prospective reserves differs from country to country. In the former USSR and in the majority of other countries that adopted this classification, prospective reserves are divided into categories P1, P2 and P3. However, in the classification used in Poland, on which this paper is based, prospective reserves are divided into prognostic reserves in categories D1, D2 and D3 and theoretical reserves in category E, categories D1 and D2 being equivalent to categories P1 and P2 respectively and combined categories D3 and E roughly equivalent to category P3. Included in category D1 are reserves either in areas adjoining documented reserves classified in category C2 or reserves that occur at depths considered to be uneconomic. Assigned to category D2 are reserves inferred from surface showings and indirect indications and quantified on the basis of statistical analysis of reserves known in similar mineralized structures in the proximity, whilst category D3 includes reserves inferred from indirect indications alone. Finally, theoretical reserves E are deducted only from regional structural, lithological, metallogenic and other considerations.
Reserves in categories D2 and above are divided along the ordinate into economic and uneconomic on the basis of the so-called criteria of balance defined by authorities in charge of the project(s). In centrally-planned economies the selection of these criteria generally reflected prevailing economic policies and priorities rather than profit considerations. Another set of criteria called the criteria of workability is then applied to economic reserves to define mineable reserves and these are called industrial reserves.
Put in the context of the IMM definitions, categories A and B are equivalent to measured mineral resources, categories C1 and C2 are broadly comparable to indicated mineral resources, whilst prospective reserves straddle the fields covered by indicated resources and mineral potential. Industrial reserves are comparable to the mineral reserve category as defined by the IMM definitions.
