mineral resources1

MINERALS


General Classification of
Nonrenewable Mineral
The U.S. Geological Survey classifies mineral
Resources


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


General Classification of
Nonrenewable Mineral
Resources
Examples are fossil


fuels (coal, oil),
metallic minerals
(copper, iron), and

nonmetallic minerals
(sand, gravel).

Figure 15-7


GEOLOGIC PROCESSES




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).


Erosion
Transportation

Weathering
Deposition

Igneous

rock Granite,
pumice,
basalt

Sedimentar
y rock
Sandstone,
limestone

Heat,
pressure
Cooling
Heat, pressure,
stress

Magma
(molten rock)

Melting

Metamorphic rock
Slate, marble,
gneiss, quartzite

Fig. 15-8, p. 343


ENVIRONMENTAL EFFECTS OF
USING MINERAL RESOURCES




Minerals are removed through a variety of methods that
vary widely in their costs, safety factors, and levels of
environmental harm.
A variety of methods are used based on mineral depth.
 Surface

mining: shallow deposits are removed.
 Subsurface mining: deep deposits are removed.


Mining Regulations


The General Mining Act of 1872 is a United States
federal law that authorizes and governs prospecting
and mining for economic minerals, such as gold,
platinum, and silver, on federal public lands. This
law, approved on May 10, 1872, codified the
informal system of acquiring and protecting mining
claims on public land, formed by prospectors in
California and Nevada from the late 1840s through
the 1860s, such as during the California Gold Rush.



Open-pit Mining




Machines dig holes
and remove ores,
sand, gravel, and
stone.
Toxic groundwater
can accumulate at
the bottom.

Figure 15-11


Area Strip Mining




Earth movers strips
away overburden, and
giant shovels
removes mineral
deposit.
Often leaves highly
erodible hills of
rubble called spoil
banks.
Figure 15-12

Contour Strip Mining




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 15-13


Mountaintop Removal




Machinery removes
the tops of mountains
to expose coal.
The resulting waste
rock and dirt are
dumped into the
streams and valleys

below.

Figure 15-14


Environmental Impacts of
Mining







Acid Mine Drainage
Erosion and Sedimentation
Cyanide & Other Toxic Releases
Dust Emissions
Habitat Modification
Surface and Groundwater Contamination


Coal mining affects the
environment



Strip mining causes severe soil erosion and chemical runoff
 Acid drainage = sulfide minerals on exposed rock surfaces
react with oxygen and rainwater to produce sulfuric acid

 Mountaintop removal causes enormous damage




Coal mining harms human
health
Subsurface mining is harmful to human health
Mine shaft collapses
 Inhalation of coal dust can lead to fatal black lung disease
Costs to repair damages of mining are very high
 These costs are not included in the market prices of fossil fuels,
which are kept inexpensive by government subsidies
Mining companies must restore landscapes, but the impacts are still
severe
 Looser of restrictions in 2002 allowed companies to dump rock and
soil into valleys, regardless of the consequences







Now what do we do with
it?


Once the ore is mined and hauled to the surface, it
must be processed

 Tailings

are what is left behind once the valuable
portion of the ore is removed.
 Gangue is the commercially worthless minerals
associated with a valuable find.


Mining Impacts


Metal ores are smelted
or treated with
(potentially toxic)
chemicals to extract the
desired metal.

Figure 15-15


Gold Processing


Gold is treated with a Cyanide compound which
produces a Gold-Cyanide complex which is soluble
 Problem:

Hydrogen Cyanide gas is toxic

Hyperaccumulation


Hyperaccumulator plants accumulate inordinate
amounts of one or more Trace Elements (TE)s in
their above ground biomass.
 Hyperaccumulators

species may accumulate one or
more of a range of TEs that currently includes nickel,
manganese, zinc, cadmium, thallium, copper, cobalt
and arsenic.
 Hyperaccumulation may have applications in mining
in the future.


Natural Capital Degradation
Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources

Steps

Environmental effects

Mining

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

Exploration,
extraction
Processing

Use

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

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

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

Transportation,
purification,
manufacturing

Fig. 15-10, p. 344


Mining Waste






Subsidence is a phenomenon where the surface
collapses directly above a subsurface mine.
Spoils are the unwanted rock and other waste left
over after mining either on the surface or
subsurface
Tailings are the materials left over after the
process of separating the valuable fraction from the
worthless fraction of an ore.


What to do with the
waste


Incorporate the mine waste into
 Concrete

for buildings
 Backfill for roads
 Extraction of other minerals

ENVIRONMENTAL EFFECTS OF
USING MINERAL RESOURCES



The extraction, processing, and use of mineral
resources has a large environmental impact.
Figure 15-9


SUPPLIES OF MINERAL
RESOURCES




The future supply of a resource depends on its
affordable supply and how rapidly that supply is used.
A rising price for a scarce mineral resource can
increase supplies and encourage more efficient use.


SUPPLIES OF MINERAL
RESOURCES


Depletion curves for a
renewable resource

using three sets of
assumptions.
 Dashed

vertical lines
represent times when
80% depletion occurs.

Figure 15-16