ore reserves and mineral resources 2011 report - Anglo American ...

SECURING OUR FUTURE
ORE RESERVES AND MINERAL RESOURCES
ORE RESERVES AND MINERAL
RESOURCES DEFINITIONS
The Ore Reserves and Mineral Resources of the Group are classified,
verified and reported on in accordance with statutory, stock-exchange
and industry/professional guidelines. The classifications are based on
the South African Code for the reporting of exploration results,
Mineral Resources and Mineral Reserves (SAMREC, 2007) and on
the code of the Joint Ore Reserves Committee (JORC) of the
Australian Institute of Mining and Metallurgy.
Reporting is by professionals with appropriate experience in the
estimation, economic evaluation, exploitation and reporting of Ore
Reserves and Mineral Resources relevant to the various styles of
mineralisation under consideration. The Group’s experience with the
various orebodies it is engaged in evaluating and mining spans
decades, resulting in a thorough understanding of the factors
relevant to assessing their economic potential.
Where Ore Reserves and Mineral Resources have been quoted for
the same property, Resources are reported both inclusive and
exclusive of the material converted to Reserves, ie one table reports
Resources that exclude those Resources converted to Reserves
while the other includes the converted Resources.
Attention is drawn to the fact that Resources are reported over a
minimum practical mining width (SAMREC, clause 21), because the
widths of the Merensky and the UG2 reefs are generally less than
70 centimetres. In the case of the UG2 Reef, however, there are many
areas where additional hanging-wall dilution is also included owing to
geotechnical considerations; this additional low-grade material usually
has a width of less than 30 centimetres, but this may increase locally to
as much as one metre. The UG2 Reef, particularly in the Eastern Limb,
may also contain pyroxenite lenses of internal waste and these are
included as dilutants in the Resource declaration. The Mineral
Resources are estimated over a practical minimum mining width
suitable for the deposit known as the ‘Resource Cut’. The minimum
mining width over which Mineral Resources are declared is 90
centimetres. The ‘Resource Cut’ width takes cognisance of the mining
method and geotechnical aspects in the hanging wall or footwall of
the reef. The conversion of the Resource Cut to an appropriate
Reserve width would include additional dilution incurred as the result
of mining considerations.
All Mineral Resources are reported after appropriate known and
unknown geological losses have been excluded.
The technique of density determination in laboratories is currently
under investigation. Reef-specific corrections might be applicable in
future Resource statements. Current indications are that the present
pycnometer method might have a slight positive bias (