Geology and Nonrenewable

Mineral Resources

The earth is made up of a core, mantle, and crust and is constantly changing as a result of processes taking place on and below its surface.

The earth’s interior consists of: Core: innermost zone with solid inner core and

molten outer core that is extremely hot. Mantle: solid rock with a rigid outer part

(asthenosphere) that is melted pliable rock. Crust: Outermost zone which underlies the

continents.

Major features of the earth’s crust and upper mantle.

Figure 15-2Figure 15-2

Fig. 15-3, p. 337

Spreading center Ocean

trench

Plate movement

Subduction zone

Oceanic crust

Continental crust

Continental crust

Material cools as it reaches

the outer mantle

Cold dense material falls back through

mantleHot

material rising

through the

mantle

Mantle convection

cell

Two plates move towards each other. One is subducted back into the mantle on a falling convection current.

Mantle

Hot outer core Inner

core

Plate movement

Collision between two continents

Tect

onic

pl

ate

Oceanic tectonic

plate

Oceanic tectonic plate

Oceanic crust

Huge volumes of heated and molten rack moving around the earth’s interior form massive solid plates that move extremely slowly across the earth’s surface. Tectonic plates: huge rigid plates that are

moved with convection cells or currents by floating on magma or molten rock.

Figure 15-4Figure 15-4

The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart at divergent plate boundaries and slide past at transform plate boundaries.

Figure 15-4Figure 15-4

Fig. 15-4, p. 338

The San Andreas Fault is an example of a transform fault.

Figure 15-5Figure 15-5

Weathering is an external process that wears the earth’s surface down.

Figure 15-6Figure 15-6

The earth’s crust consists of solid inorganic elements and compounds called minerals that can sometimes be used as resources. Mineral resource: is a concentration of

naturally occurring material in or on the earth’s crust that can be extracted and processed into useful materials at an affordable cost.

The U.S. Geological Survey classifies mineral resources into four major categories: Identified: known location, quantity, and quality

or existence known based on direct evidence and measurements.

Undiscovered: potential supplies that are assumed to exist.

Reserves: identified resources that can be extracted profitably.

Other: undiscovered or identified resources not classified as reserves

Examples are fossil fuels (coal, oil), metallic minerals (copper, iron), and nonmetallic minerals (sand, gravel).

Figure 15-7Figure 15-7

Deposits of nonrenewable mineral resources in the earth’s crust vary in their abundance and distribution.

A very slow chemical cycle recycles three types of rock found in the earth’s crust: Sedimentary rock (sandstone, limestone). Metamorphic rock (slate, marble, quartzite). Igneous rock (granite, pumice, basalt).

Fig. 15-8, p. 343

Erosion

Transportation

Weathering

Deposition

Igneous rock Granite, pumice, basalt

Sedimentary rock Sandstone, limestone

Heat, pressure

Cooling

Heat, pressure, stress

Magma (molten rock)

Melting

Metamorphic rock Slate, marble, gneiss, quartzite

The extraction, processing, and use of mineral resources has a large environmental impact.

Figure 15-9Figure 15-9

Fig. 15-10, p. 344

Natural Capital Degradation

Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources

StepsSteps Environmental effectsEnvironmental effects

Mining Disturbed land; mining accidents; health hazards, mine waste dumping, oil spills and blowouts; noise; ugliness; heat

Exploration, extraction

Processing

Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat

Transportation, purification, manufacturing

Use

Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat

Transportation or transmission to individual user, eventual use, and discarding

A variety of methods are used based on mineral depth. Surface mining: shallow deposits are removed.

Remove overburden Discard as waste material (spoils) Examples:

Open-pit mining, area strip mining, contour strip mining, mountain-top removal

Subsurface mining: deep deposits are removed.

Machines dig holes and remove ores, sand, gravel, and stone.

Toxic groundwater can accumulate at the bottom.

Figure 15-11Figure 15-11

Earth movers strips away overburden, and giant shovels removes mineral deposit.

Often leaves highly erodible hills of rubble called spoil banks. Succession slow after

mining – no topsoil Desertification in arid

areas

Figure 15-12Figure 15-12

Used on hilly or mountainous terrain.

Unless the land is restored, a wall of dirt is left in front of a highly erodible bank called a highwall.

Figure 15-13Figure 15-13

Machinery removes the tops of mountains to expose coal.

Resulting waste rock and dirt are dumped into the streams and valleys below. Causes flood hazards Leaches toxic metals

into waterways Increasing in WV and

KY Figure 15-14Figure 15-14

before after

Larry Gibson on Larry Gibson on the issuethe issue

A positive A positive view view

Scarring and disruption of the land surface

Subsidence Toxin laced mining

wastes Air pollution Acid deposition from

smelting gases

Figure 15-15Figure 15-15

The future supply of a resource depends on its affordable supply and how rapidly that supply is used.

Never completely run out Economic depletion – costs

more to find, extract, transport, and process the remaining deposit than it is worth.

Options: Recycle/reuse Waste less Use less Find a substitute Do without

A rising price for a scarce mineral resource can increase supplies and encourage more efficient use.

Depletion curves for a renewable resource using three sets of assumptions. Dashed vertical

lines represent times when 80% depletion occurs.

Figure 15-16Figure 15-16

Mining no longer a free market Subsidized for depletion Consumer pays via taxes

New technologies can increase the mining of low-grade ores at affordable prices, but harmful environmental effects can limit this approach. Biomining – slow, but environmentally less destructive

Ocean mineral resources Cost too much to extract Squabbles over who owns them (i.e. deposits in

international waters) Environmental effects are poorly understood

Seawater Continental shelf

deposits Hydrothermal vent

deposits Manganese

nodules

Figure 15-17Figure 15-17

Fig. 15-18, p. 351

Solutions

Sustainable Use of Nonrenewable Minerals

• Do not waste mineral resources.

• Recycle and reuse 60–80% of mineral resources.

• Include the harmful environmental costs of mining and processing minerals in the prices of items (full-cost pricing).

• Reduce subsidies for mining mineral resources.

• Increase subsidies for recycling, reuse, and finding less environmentally harmful substitutes.

• Redesign manufacturing processes to use less mineral resources and to produce less pollution and waste.

• Have the mineral-based wastes of one manufacturing process become the raw materials for other processes.

• Sell services instead of things.

• Slow population growth.

Growing signs point to an ecoindustrial revolution taking place over the next 50 years.

The goal is to redesign industrial manufacturing processes to mimic how nature deals with wastes. Industries can interact in complex resource

exchange webs in which wastes from manufacturer become raw materials for another.

Figure 15-19Figure 15-19