Download PPT link ch 14

Terrestrial Earth
Plate Tectonics, Minerals, Rocks &
Mining
Plate tectonics shapes the
Earth
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Plate tectonics = process that underlies earthquakes and
volcanoes and that determines the geography of the Earth’s
surface
Crust = lightweight thin component of Earth’s surface
Mantle = malleable layer on which the crust floats
Core = molten heavy center of Earth made mostly of iron
Pangaea: the
supercontinent
Pangaea = at least
twice in Earth’s
history, all
landmasses were
joined in one
supercontinent
Earth’s crust is
constantly created and
destroyed
Divergent plate
boundaries
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= magma surging upward to
the surface divides plates and
pushes them apart, creating
new crust as it cools and
spreads
Transform plate boundary
= two plates meet, slipping
and grinding alongside one
another
– Friction spawns earthquakes
along slip-strike faults
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Tectonic plates can
collide
Convergent plate boundaries
= where plates collide
Subduction = one plate of
crust may slide beneath another
– Magma erupts through the
surface in volcanoes
Two colliding plates of
continental crust may lift
material from both plates
– Resulted in the Himalaya
and Appalachian mountains
Boundary Interactive
Boundary Animations
The Earth has 15 major
tectonic
plates
Movement of these plates influences climate and evolution
Minerals and Rocks
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What is a mineral?
– naturally occurring, inorganic, solid element or compound
with a definite chemical composition and a regular internal
crystal structure
What is rock?
– solid, cohesive, aggregate of one or more minerals
– Each rock type has a characteristic mixture of minerals
What is an Ore?
– Rock with large concentration of a particular maineral to
make it profitable
– High and low grade ores
» NON- Metalic Mineral

Sand, gravel, limestone
» Metalic

Aluminum, Steel, manganese, cobalt, chromium, Copper, Gold
Minerals
Transport
Erosion
Weathering
Igneous Rock
Granite, Pumice,
Basalt
Deposition
Sedimentary Rock
Shale, Sandstone,
Limestone
Rock
Heat,
Cycle Pressure
Heat,
Metamorphic Rock
Pressure
Slate, Quartzite,
Marble
Magma
(Molten Rock)
Fig. 16-9 p. 339
Mining: Extract Ore from Ground
Types of Mining:
• Surface Mining: Scoop ore off surface or earth.
• cheap.
• safe for miners.
• large environmental destruction.
• Sub-Surface or Underground Mining: Use of shafts to reach
deeply buried ores.
• expensive.
• hazardous for miners.
• less environmental damage.
Surface Mining
open pit mining:
• circular hole in ground, with ramp
circling down along sides, allows
deeper ore to be reached.
Surface Mining- Strip Mining
strip-mining:
scoop off
rock overburden, and then
scoop off ore material.
• Economics of strip mining
depend on stripping ratio
• Large land area can be involved,
especially for coal and bauxite.
Results of Mining
utube
Bauxite Mine
In the Earth's Crust, in every million atoms, around 82 000 of them are
Aluminum, (82 000 ppm1), by weight. This is around 8 % or almost one
in every 12 atoms. This places aluminum amongst the world's most
abundant elements.
Despite being present of Earth in such incredibly vast quantities on
Earth, the metal never occurs on it's own in nature. Instead of existing
free like Gold and Silver, due to its higher level of reactivity, it is always
chemically bonded in compounds when it normally occurs. The most
common of these compounds is Bauxite, or Aluminum Ore which
contains large quantities of Aluminum Oxide.
Mountain Top Removal
Removing
Overburden
spoils
Overburden
Coal seem
bedrock
Appalachian Voices
http://www.youtube.com/watch?v=aiSzOiGFa-0
https://www.youtube.com/watch?v=ohrrE1rjzLo
Gold in Quartz
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A large quartz boulder with a lot of visible gold.
Usually, the gold is much finer and hard to see.
Placer Deposition
Panning for
gold in a
placer
deposit
Aeolian Placers
The "diamond crawl" in a
deflation basin, Diamond
Area No 1, Namibia
 Diamond concentrations
were increased by wind
erosion
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Environmental Impact of
Mining
Waste water/sludge dams
Underground Mining
• A technology originating in antiquity.
• A variety of configurations, depending upon conditions
Acid Mine Drainage
Environmental Impact of
Mining
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Scaring the land surface- result spoils banks
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Soil poor, windblown .. Primary succession slow
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Toxic wastewater stored in sludge dams.
– Toxins include slenium, arsenic, and mercury
Cassiterite
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tin oxide ore mineral, SnO2. It is generally
opaque but is translucent in thin crystals. Its
luster and multiple crystal faces produce a
desirable gem. Cassiterite has been the chief
tin ore throughout ancient history and
remains the most important source of tin
today
TinSoldiers
Nonrenewable
Mineral
Resource
Depletion
Curves
Source: Miller, G. Tyler, Living In The
Environment. (2000) Wadsworth
Publishing. New York.
Nonrenewable
Mineral
Resource
Depletion
Curves
Source: Miller, G. Tyler, Living In The
Environment. (2000) Wadsworth
Publishing. New York.
US Non-renewable Resource
Reserves
Source: Miller, G. Tyler, Living In The Environment. (2000) Wadsworth
Publishing. New York.
Mining is an Economic Activity
The decision to mine (or not to mine) a particular
ore deposit depends upon:
1. an analysis of costs, benefits and risks
2. tangible (i.e. dollar profit)
3. intangible (i.e. hopes of stimulating the economy, fears
of environmental damage)
Gradual shift toward surface mining
Surface mining
Minining Law
http://www.youtube.com/watch?v=ofN1aLMwcUI
Mining around the world
Hungary’s disaster
China’s rare earth minerals
US rare earth mineral info ad
Proposal for New Massive Mine in Romania
Goldmining
Mining ore
Bauxite mining
Mountaintop removal
Mining
Issues
Mine Safety:
In U.S., stringent
mining regulations
have lead to a
reduction in
fatalities, both in
terms of total deaths
per year, deaths per
person-hour
worked, and deaths
per ton mined.
surface
Acid Mine Drainage
Health Problems
• collapse of mine.
• fire (methane, coal dust, etc.).
• asphyxiation (methane, carbon monoxide, etc.).
• pneumoconiosis (from inhaling coal dust).
• asbestosis (from inhaling asbestos fibers).
• silicosis (from inhaling silicate dust).
• heavy metal poisoning (e.g. mercury).
• radiation exposure (in uranium mining).
Environmental Damage
• Gaping holes in ground (old open pit mines).
• Piles of mine tailings (non-ore removed from mines).
• Accidental draining of rivers and lakes.
• Disruption of ground water flow patterns.
• Loss of topsoil in strip-mined regions (350 to 2,700 km2 in
US alone).
• Contamination from sulfuric acid (H2SO4) produced
through weathering of iron sulfide (FeS2, pyrite) in tailings.
4FeS2 + 14H2O = 4Fe(OH)3 + 8H2SO4
• Contamination from heavy metals (e.g. arsenic, mercury)
in mine tailings.
Smelting and Refining:
Environmental Problems
1. Production of huge piles of slag.
2. Emission of CO2, a greenhouse gas, into the
atmosphere.
3. Pollution associated with the generation of electricity
needed in anode furnaces (especially aluminum).
4. Sulfur dioxide emissions from the refining of sulfide
ores are a major source of air pollution. The sulfur
dioxide combines with water to produce sulfuric acid.
5. Release of heavy metals (As, Cd, Hg), present in trace
quantities in sulfide ores, into the atmosphere.
Cost Trends
• Amount of commodities mined per year has generally
increased.
• Commodity prices can take big swings, but average prices
during the last century often declined or remained constant.
Cents per pound
copper
Ore grades have all
decreased as
milling technology
has improved