Geology Reference
In-Depth Information
interest in a mineral, there is no investment wasted in its exploration. Hence,
a real or perceived mineral scarcity often has an economic origin rather than a
geological one. A clear example of this is that of mercury. Its decline in con-
sumption, except for in small-scale gold mining, forced companies to curve and
finally stop production (see Fig. 13.36), as is the case for the Spanish Almaden
mine, once the leading producer, where mining ceased in 2003. Consequently,
production is said to follow an economic-driven bell-shaped curve. Commodi-
ties with similar stories are those of arsenic, beryllium, antimony or radioactive
minerals (mainly uranium and thorium).
Concentration of supply: as claimed by Moss et al. (2011), where the struc-
ture of supply is monopolistic or dominated by only a few players, individual
large supplier countries have su
cient market power to affect global production
and price thresholds as in the case of rare earths, antimony or fuel minerals,
particularly oil and natural gas.
Byproduct character: when the mineral is a byproduct, production decisions
may be driven by the economics of the host-metal and hence the curves do
not necessarily follow typical bell-shaped curves. This aspect is especially pro-
nounced at the local scale as the reader will see in the case of Australian silver,
lead and zinc deposits.
Technological factors: this category relates to the ability to substitute and
recycle minerals. The general trend observed is that these factors only slightly
affect a commodity's production pattern. For instance, in the case of aluminium
or iron (see Fig. 13.38), where recycling rates are high, the effect of recycling
is imperceptible due to the continual growth in demand for new raw-material.
Nevertheless, substitution and recycling could become more critical into the
next decades when scarcity becomes more acute. Once the peak of a mineral
has been reached (or when it is in sight), the sought for alternative materials
and recycling is enhanced so as to reduce production costs. The result is that
the curve is asymmetrical, given that the section right of the peak falls more
rapidly than the left climbed.
The authors however firmly recognise that the absolute limiting factor, regardless
of all other activity, is and will always be the geological availability of the resource.
Generally speaking, the Hubbert Peak Model can be rather satisfactorily applied
to those minerals, where the concentration factor is not important, i.e. to liquid
and gaseous fossil fuels. However, there have been a few prominent studies relating
the application of the Hubbert model to non-fuel minerals. Meadows et al. (1972)
applied exponential-like curves to the production of various different commodities.
Roberts and Torrens (1974) meanwhile, used the model to examine the production
cycle of copper. Arndt and Roper (1977) examined peak data of 35 non-renewable
minerals in the U.S. and worldwide. Such studies, given the lack of information re-
garding consumption rates or future reserve estimates at the time (essential aspects
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