302 CHAPTER 12 Mineral and Soil Resources
- Contrast the consumption of minerals by
developing and highly developed countries. - Distinguish between surface mining and
subsurface mining, using the terms overburden
and spoil bank in your answer. - Describe briefly the process of smelting.
arth’s outermost layer, the crust, contains
many kinds of minerals that are of economic
importance. We now focus on the economic
and environmental impacts of extracting
and using mineral resources. We then consider soil, the
part of the crust where biological and physical pro cesses
meet.
Minerals are such an integral part of our lives that
we often take them for granted. Steel, an essential build-
ing material, is a blend of iron and other metals. Bever-
age cans, aircraft, automobiles, and buildings all contain
alu minum. Copper, which readily conducts electricity,
is used for electrical and communications wiring. The
concrete used in buildings and roads is made from sand
and gravel, as well as cement, which contains crushed
limestone. Sulfur, a component of sulfuric acid, is an in-
dispensable industrial mineral used to make plastics and
fertilizers, and to refine oil. Other impor tant minerals
include platinum, mercury, manganese, and titanium.
Tantalum, a rare hard metal that is resistant to corrosion,
has recently become important to the production of ca-
pacitors in a range of electronic devices. (See the Case
Study at the end of the chapter for more on this mineral,
including its ties to conflict in the Democratic Republic
of the Congo.)
Earth’s minerals are elements or (usually) com-
pounds of elements and have precise chemical composi-
tions. Sulfides are mineral compounds in which certain
elements are combined chemically with sulfur, and oxides
are mineral compounds in which elements are combined
chemically with oxygen. Minerals are metallic or nonme-
tallic (Figure 12.5). Metals are minerals such as iron,
aluminum, and copper, which are malleable, lustrous,
and good conductors of heat and electricity. Nonmetallic
minerals, such as sand, stone, salt, and phos phates, lack
these characteristics.
Economic Geology: Useful Minerals
LEARNING OBJECTIVES
Rocks are naturally formed mixtures of minerals that
have varied chemical compositions. Ore is rock that con-
tains a large enough concentration of a particular min-
eral to be profitably mined and extracted. High-grade
ores contain relatively large amounts of particular min-
erals, whereas low-grade ores contain lesser amounts.
Although some minerals are abundant, all minerals are
nonrenewable resources that are not replenished by nat-
ural processes on a human timescale.Minerals: An Economic Perspective
At one time, most of the highly developed nations had
abundant mineral deposits that enabled them to indus-
trialize. In the process of industrialization, these coun-
tries largely depleted their domestic reserves of minerals
so that they must increasingly turn to developing coun-
tries. This is particularly true for countries in Europe,
Japan, and, to a lesser extent, the United States.
The level of mineral consumption varies widely
between highly developed and developing coun tries.
The United States and Canada, which have about 5.1
percent of the world’s population, consume about one-
fourth of many of the world’s metals. It is too sim plistic,
however, to divide the world into two groups, the mineral
consumers (highly developed countries) and the mineral
producers (developing countries). Many of the world’s
top mineral producers are highly developed countries
and top mineral consumers (for example, the United
States, Canada, Australia, and Russia). Many developing
countries, however, lack any significant mineral deposits.
Mineral production and consumption in China is in-
creasing dra matically as the country industrializes. For ex-
ample, China smelted more than 34 percent of the world’s
primary aluminum (obtained from ores, not recycling).
China also con sumes almost all of this aluminum, making
it the world’s largest producer and largest consumer of
primary aluminum. As China’s mineral production and
economic growth expand, the natural capital on which its
economic growth is based is being degraded. Recall from
Chapter 3 that natural capital is Earth’s resources and
processes that sustain humans and other living organisms
(see Fig ure 3.14). Natural capital includes minerals, soils,
fresh water, clear air, forests, wildlife, and fisheries.E