Mineral resource classification is the classification of mineral deposits based on their geologic
certainty and economic value.
Mineral deposits can be classified as: Mineral resources that are potentially valuable,
and for which reasonable prospects exist for eventual economic extraction.
Mineral reserves or Ore reserves that are valuable and legally and economically and
technically feasible to extract In common mining terminology , an "ore deposit"
by definition must have an 'ore reserve', and may or may not have additional 'resources'.
Classification, because it is an economic function, is governed by statutes, regulations
and industry best practice norms. There are several classification schemes worldwide,
however the Canadian CIM classification, the Australasian Joint Ore Reserves Committee
Code, the South African Code for the Reporting of Mineral Resources and Mineral Reserves
and the “chessboard” classification scheme of mineral deposits by H. G. Dill are the
general standards.
Mineral resources A 'Mineral Resource' is a concentration or
occurrence of material of intrinsic economic interest in or on the earth's crust in such
form, quality and quantity that there are reasonable prospects for eventual economic
extraction. Mineral Resources are further sub-divided, in order of increasing geological
confidence, into inferred, Indicated and measured Categories.
Inferred Mineral Resource is that part of a mineral resource for which tonnage, grade
and mineral content can be estimated with a low level of confidence. It is inferred
from geological evidence and assumed but not verified geological/or grade continuity. It
is based on information gathered through appropriate techniques from location such as outcrops,
trenches, pits, workings and drill holes which may be of limited or uncertain quality and
reliability. Indicated resources are simply economic mineral
occurrences that have been sampled to a point where an estimate has been made, at a reasonable
level of confidence, of their contained metal, grade, tonnage, shape, densities, physical
characteristics. Measured resources are indicated resources
that have undergone enough further sampling that a 'competent person' has declared them
to be an acceptable estimate, at a high degree of confidence, of the grade, tonnage, shape,
densities, physical characteristics and mineral content of the mineral occurrence.
Resources may also make up portions of a mineral deposit classified as a mineral reserve, but:
Have not been sufficiently drilled out to qualify for Reserve status; or
Have yet to meet all criteria for Reserve status
Mineral reserves/Ore Reserves Mineral reserves are resources known to be
economically feasible for extraction. Reserves are either Probable Reserves or Proved Reserves.
A Probable Ore Reserve is the part of Indicated resources that can be mined in an economically
viable fashion, and in some circumstances, a Measured Mineral Resource. It includes diluting
material and allowances for losses which may occur when the material is mined. A Probable
Ore Reserve has a lower level of confidence than a Proved Ore Reserve but is of sufficient
quality to serve as the basis for decision on the development of deposit.
A Proved Ore Reserve is the part of Measured resources that can be mined in an economically
viable fashion. It includes diluting materials and allowances for losses which occur when
the material is mined. A Proved Ore Reserve represents the highest
confidence category of reserve estimate. The style of mineralization or other factors could
mean that Proved Ore Reserves are not achievable in some deposits.
Generally the conversion of resources into reserves requires the application of various
modifying factors, including: mining and geological factors, such as knowledge
of the geology of the deposit sufficient that it is predictable and verifiable; extraction
and mine plans based on ore models; quantification of geotechnical risk—basically, managing
the geological faults, joints, and ground fractures so the mine does not collapse; and
consideration of technical risk—essentially, statistical and variography to ensure the
ore is sampled properly: metallurgical factors, including scrutiny
of assay data to ensure accuracy of the information supplied by the laboratory—required because
ore reserves are bankable. Essentially, once a deposit is elevated to reserve status, it
is an economic entity and an asset upon which loans and equity can be drawn—generally
to pay for its extraction at a profit; economic factors;
environmental factors; marketing factors;
legal factors; political factors;and
social factors See also
Mineral exploration Ore genesis
Ore Drilling rig
National Instrument 43-101 References
External links JORC Code
University of Western Australia Mining Law Centre
U.S. Geological Survey Circular 831, Principles of a Resource/Reserve Classification for Minerals
Canadian Institute of Mining, Metallurgy and Petroleum - CIM Definition Standards - On
Mineral Resources and Mineral Reserves The Canadian Council of Professional Geoscientists
CCPG NI 43-101 Guidelines
The South African SAMVAL and SAMREC Codes