Page 35 - Introduction to Mineral Exploration

18 C.J. MOON & A.M. EVANS

Figures 1.12 and 1.13 show a general increase would probably not be mineable under existing
in exploration expenditure over recent decades, transportation, infrastructure, and production
and Cook (1987) records that expenditure in the costs.
noncommunist world rose from about $400M In existing mining districts smaller targets
in 1960 to over $900M in 1980 (constant 1982 can be selected, especially close to working
US$). This increase is partially due to the use mines belonging to the same company, or a
of more costly and sophisticated exploration company might purchase any new finds. These
methods, for example it has been estimated brownfield finds can be particularly import-
that of deposits found in Canada before 1950, ant to a company operating a mine that has
85% were found by conventional prospecting. only a few years of reserves left and, in such a
The percentage then dropped as follows: 46% case with an expensive milling plant and per-
in 1951–55, 26% in 1956–65, 10% in 1966–75, haps a smelter to supply, an expensive satura-
and only 4% during 1971–75. A review by tion search may be launched to safeguard the
Sillitoe (1995, updated in 2000) of discoveries future of the operation. Expenditure may then
in the Circum-Pacific area showed that geo- be much higher for a relatively small target
logical work, particularly intimate familiarity than could be justified for exploration in virgin
with the type of deposit being sought, was the territory.
key to success. Blain (2000) concurs on the im-
portance of geological work and his analysis
shows that geology took over from prospecting 1.7 FURTHER READING
as the dominant factor in exploration success
in approximately 1970. An excellent summary of the definitions and
usages of the terms mineral resources and ore
reserves is to be found in the paper by Taylor
1.6.4 Economic influences
(1989) and the more formal JORC (Australasian
Nowadays the optimum target (section 1.2.3, JORC 2003). The two books by Crowson –
“Metal and mineral prices”) in the metals sec- Inside Mining (1998) and Astride Mining (2003)
tor must be a high quality deposit of good ad- – provide stimulating reading on mineral mar-
dress, and if the location is not optimal then an kets and more general aspects of the mineral
acceptable exploration target will have to be industry, including mineral exploration. Break-
of exceptional quality. This implies that for ing New Ground (MMSD 2002) provides a very
base metal exploration in a remote inland part detailed background to the mineral industry
of Australia, Africa, or South America a large and how environmental and social issues might
mineral deposit must be sought with a hundred be addressed.
or so million tonnes of high grade resources or Readers may wish to follow developments in
an even greater tonnage of near surface, lower mineral exploration using websites such as
grade material. Only high unit value industrial Infomine (2004) and Reflections (2004), as well
minerals could conceivably be explored for in as material also available in printed form in the
such an environment. Anything less valuable weekly Mining Journal and Northern Miner.