The Future of Economic Geology - Metals and Society: An Introduction to Economic Geology - page 151

recently formed, still submerged exhalative sulfide deposits will provide a source of
Cu, Zn, Pb, au and other metals.
But before these deposits can be mined they must be found. as explained in the
first chapter, known reserves of most metals are enough to meet the world's
consumption for only the next few decades. At present, and most probably through
the first part of this century, national and international mineral exploration
companies will conduct the search for new deposits, assisted in many regions by
national geological surveys. The goal of most companies will be to find better
deposits; i.e. deposits with relatively high grades and geological settings that will
allow them to be mined easily and efficiently. The driving force for this search is of
course profit, the raison d'ˆtre of a private company, but other factors come into
play. The mining of a large low-grade ore body involves the extraction of vast
amounts of rock, with consequent use of large amounts of energy, water and other
resources. To extract copper from ore containing 0.4% Cu produces well over twice
as much waste as ore containing 0.8% Cu (over half because the recovery of the
metal is not 100% efficient) and the waste must be disposed of or retained. The
environmental impact of mining rich ore is therefore less than that of mining poor
ore. The environmental consequences of a mining operation now play an important
role in the planning and execution of any new mine. One interesting example of
these concerns is the developments of processes in which the wastes produced by
the mining of deposits in mafic or ultramafic rock are reacted with CO 2 from
furnaces or from the air, fixing the greenhouse gas as stable carbonates and thereby
offsetting the carbon footprint of the mining operation.
The techniques used in this search for new deposits are rapidly evolving, with
ever greater reliance being placed on remote sensing techniques and geophysical
methods capable of finding deposits hidden beneath surface layers of sediment,
alluvium or deep tropical weathering. The mode of operation of the major
companies is currently changing and there has been an unfortunate tendency for
them to abandon active exploration and research, leaving these tasks to junior
companies and to academics. Yet, at one level or another, geologists will continue
to play an important role in the industry.
In the past year, a growing demand for metals had fuelled an increase in metal
prices that encouraged companies all around the globe to ramp up their exploration
programs. The companies require geologists for this work and they will meet this
requirement by hiring competent people wherever they can. One of our reasons for
writing this topic is to provide at least a basic knowledge of the subject to students
graduating from universities. This knowledge should prove useful not only for
those few students who find employment in the industry, but also for all the others
who, no matter which profession they find themselves in, should know a little about
the role of metals in our society and about how the ore that yield them form and are
mined.