CHAPTER 12:
GEOLOGY AND NONRENEWABLE MINERAL RESOURCES
Objectives
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Briefly describe the layers of the Earth’s interior. Describe the internal and external Earth processes responsible for forming
Earth’s landscape. Be sure to distinguish three different tectonic plate boundaries and the geologic features often found at
each. Explain how this knowledge is significant for understanding mineral deposit formation and the origin of some natural
hazards.
List and define the three kinds of rock types, and note some of the common mineral resources associated with them. Briefly
describe the rock cycle and indicate interrelationships among these classes.
Distinguish between mineral resources, mineral reserves, and mineral ore deposits. Discuss mineral economics in terms of
supply, demand, price, and economic depletion. Note the role of government policies on mineral economics.
Distinguish between surface and subsurface mining. Briefly describe three types of surface mining. Discuss the
environmental impacts of mining and processing of ore deposits, particularly metallic minerals.
Discuss the potential effects of finding material substitutes for mineral products, recycling and reusing mineral products, and
reduced consumption through new technology.
Key Terms {(Terms are listed in the same font style as they appear in the text.)}
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acid mine drainage (p. 271)
area strip mining (p. 269)
asthenosphere (p. 262)
biomimicry (p.276)
biomining (p. 274)
brownfields (p.276)
continental crust (p. 262)
continental glaciers (p. 265)
contour strip mining
(p. 270)
convection cells or
currents(p. 262)
convergent plate boundaries
(p. 263)
core (p. 262)
depletion time (p. 272)
divergent plate boundaries
(p. 263)
ecoindustrial revolution
(p. 276)
economically depleted
(p. 272)
erosion (p. 264)
external processes(p. 264)
fossil fuels(p. 266)
gangue (p. 271)
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geology (p. 262)
glaciers (p. 265)
high-grade ore (p. 267)
highwall (p. 270)
identified resources (p.
266)
igneous rock (p. 267)
industrial ecology (p. 276)
internal processes (p. 263)
limestone (p. 266)
lithosphere (p. 263)
low-grade ore (p267)
manganese nodules (p. 274)
mantle (p. 262)
materials revolution (p. 274)
metallic minerals (p. 266)
metamorphic rock (p. 267)
mineral (p. 274)
mineral resource (p. 266)
mountaintop removal
(p. 270)
nonmetallic minerals(p. 266)
nonrenewable mineral
resource (p. 266)
oceanic crust (p. 262)
oceanic ridges(p. 263)
open-pit mining (p. 269)
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ore (p. 266)
overburden (p. 269)
phosphate salts (p. 266)
reserves (p. 266)
resource exchange webs
(p. 275)
rock (p. 266)
rock cycle (p. 267)
scarring (p. 270)
sedimentary rock (p. 267)
smelting (p. 271)
spoils or spoil banks (p.
269)
strategic mineral resources
(p. 272)
strip mining (p. 269)
subduction (p. 263)
subduction zone (p. 263)
subsidence (p. 271)
subsurface mining (p. 269)
surface mining (p. 269)
tailings (p. 271)
tectonic plates (p. 263)
transform fault (p. 263)
trench (p. 263)
tsunamis (p. 263)
weathering (p.264)
Outline
12-1 Geologic Processes:
A. Geology is the study of dynamic processes occurring on the Earth’s surface and in its interior.
1. The surface of the Earth is composed of a series of gigantic plates that move very slowly across the Earth’s
surface.
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2. The surface features of the Earth change due to the effects of water and Earth movements.
B. The three major interior zones of the Earth are the core, mantle, and crust.
1. The crust is the thinnest layer of soil and rock that floats on a mantle of partly melted and solid rock. A physical
layer consisting of the crust and the uppermost area of the mantle is known as the lithosphere. Pieces of the
lithosphere are known as tectonic plates.
2. The core is intensely hot. It has a solid inner part surrounded by a liquid core of molten or semisolid material.
3. The mantle is a thick, solid zone. It is mostly solid rock, but an area called the asthenosphere is very hot, partly
melted rock about the consistency of soft plastic.
C. Convection currents move large volumes of rock and heat in loops within the mantle. Mantle plumes flow slowly
upward and when it reaches the top of the plume it radiates out like the top of an open umbrella.
D. About 15 rigid tectonic plates, averaging about 50 miles thick, move across the surface of the asthenosphere very
slowly.
1. The plates move at different rates, some move about one centimeter/year and others move as much as 18
centimeters (7 inches)/year.
2. The theory of plate tectonics became widely accepted in the 1960s and was developed from the idea of continental
drift.
3. The movement of these plates produces mountain chains, island arcs, ocean basins, and trenches on the ocean
floor.
4. Volcanoes and earthquakes are likely to occur at the plate boundaries.
E. There are three types of boundaries for tectonic plates. The first two boundaries are divergent plate boundaries, where
plates move apart in opposite directions, and convergent plate boundaries, where plates are pushed together by internal
forces and one plate rides up over the other. A trench generally occurs at convergent boundaries. The third type of
boundary is a transform fault and occurs where plates slide/grind past one another.
F. Movement of the tectonic plates is part of the recycling of the planet’s lithosphere, which in some cases has produced
mineral deposits.
G. External geologic processes, such as changes based on the sun and gravity, wear down the Earth’s surface
(weathering) and produce landforms controlled by erosion by water, wind, and ice.
12-2 Minerals, Rocks, and the Rock Cycle
A. The Earth’s crust is composed of minerals and rocks, and it is the source of nonrenewable resources such as soil and
metals.
1. A mineral is an element or inorganic compound that is solid with a regular internal crystalline structure.
2. A rock is a solid combination of one or more minerals consisting of igneous, sedimentary, and metamorphic rocks
that are recycled by the rock cycle.
B. Mineral resources are nonrenewable materials that we can extract from the Earth’s crust.
1. We can find and extract over 100 minerals from the Earth, such as metallic, nonmetallic, and energy resources.
2. An ore is extractable mineral resources containing one or more metallic minerals that can be mined profitably. A
high-grade ore contains a relatively large amount of the target mineral, whereas a low-grade ore contains a smaller
amount.
3. U.S. Geological Survey divides nonrenewable mineral resources into four major categories:
a. Identified resources are those with a known location, quantity, and quality.
b. Reserves are identified resources that can be extracted profitably at current prices.
c. Undiscovered reserves are potential supplies of a mineral resource assumed to exist.
d. Other resources are undiscovered resources, and identified resources not classified as reserves.
12-3 Impact of Using Mineral Resources: The environmental impact of extracting and processing mineral resources depends on
the grade—the lower the grade, the greater the environmental impact. As the higher-grade ores are depleted, more money,
energy, and other material resources are needed, and land disruption, mining waste, and pollution increases.
A. Shallow deposits are removed by surface mining, and deep deposits are removed by subsurface mining.
1. In surface mining, the overburden of rock and soil is removed and discarded. This mining method extracts about
90% of nonfuel mineral and rock deposits and 60% of the coal used in the U.S.
2. Surface mining is done by one of several methods: open-pit mines, dredging, and strip mining.
3. The Surface Mining Control and Reclamation Act of 1977 (in the U.S.) requires mining companies to restore most
surface-mined land, but mine reclamation efforts have so far been only partially successful.
4. Subsurface mining removes coal and various metal ores too deep for surface mining.
Geology and Nonrenewable Mineral Resources
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5.
Subsurface mining disturbs less than one-tenth as much land as surface mining, with less waste, but is more
dangerous and expensive.
B. Mining, processing, and using mineral resources requires large amounts of energy, causes land disturbance, and causes
air and water pollution.
1. The land is left scarred and the surface is disrupted. Cleanup may cost in the billions.
2. Subsidence from underground mining causes sewer, gas, and water systems to break.
3. Mining wastes contain toxins, and acid drainage ends up in streams and groundwater.
4. Toxic chemicals can also be discharged into the atmosphere.
C. Metal ores are extracted, purified, smelted, and made into the desired products.
1. Ore has two components: the ore mineral and the waste material called gangue.
2. Ore is separated from gangue or tailings, smelted to obtain the metal, and made into products that are then used
and discarded or recycled.
3. There can be enormous amounts of air and water pollution from these processes, particularly from the extraction
of lower grade ores, and metal smelting.
12-4 Duration of Mineral Resource Supplies: Mineral resources are unevenly distributed over the Earth’s surface. The United
States, Australia, South Africa, Russia, and Canada supply most of the nonrenewable mineral resources presently in use.
Russia, U.S., and Germany consume 75% of all the common metals used globally.
A. A nonrenewable resource generally becomes economically depleted rather than totally depleted. There are five choices
at that point: recycle or reuse existing supplies, waste less, use less, find a substitute, or do without.
B. A rising price for a scarce mineral resource can decrease supplies and encourage more efficient use.
1. Economics determines what part of a known mineral supply is extracted and used.
2. Some economists feel that price effect may no longer apply since industry and government often control the
supply, demand, and prices of minerals so that a truly competitive market does not exist.
3. Mineral prices are kept artificially low because governments subsidize development of domestic mineral
resources. In the U.S., mining companies get depletion allowances of 5–22% of their gross income. They are also
allowed to deduct much of the cost of finding and developing mineral deposits.
4. The government currently gives billions in subsidies. Critics feel that taxing extraction of nonfuel mineral
resources would create incentives for more efficient resource use, reduce waste and pollution, and encourage
recycling and reuse of these resources.
C. Lower grade ores can be mined at affordable prices with new technologies, such as biomining, which are far less
damaging to the environment.
D. Recovering minerals from seawater and the ocean floor costs more money and energy than they are presently worth,
except for magnesium, bromine, and sodium chloride, which are extracted profitably at seawater.
12-5 Sustainable Mineral Use: Some analysts believe that even if supplies of key minerals become too expensive or scarce due
to unsustainable use, human ingenuity will find substitutes.
A. Plastics have replaced copper, steel, and lead in many piping products. Fiber-optic glass cables that transmit pulses of
light are replacing copper and aluminum wires in telephone cables.
B. The major drawback for plastics is that they are extracted from fossil fuels whose extraction and processing carries a
high environmental impact price.
C. Substitutes are not the ultimate solution for mineral scarcity. Currently platinum is unrivaled as an industrial catalyst,
and chromium is still a very essential component of stainless steel.
D. Because of the reduced environmental impact, recycling and reusing metals is a more sustainable practice.
E. Modern technologies are tending toward the use of much smaller quantities of nonrenewable resources—electronics
and nanotechnology.
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