Geology, plate tectonics, mining

1. Geology and Nonrenewable
Minerals
Ch. 14, part 1

2. Lecture Tool
Read over the clues in the crossword
puzzle
During lecture, fill in the terms as they
come up
At the end of class, turn in puzzles
Two correct puzzles chosen at random
for a ticket

3. Our Earth
 Cyanide heap
leaching
 Level mountains
and crush all the
rock
 Pile it up and spray
it with cyanide salts
 Drain the solution
into storage ponds
 Extract the tiny bit
of gold in them
 Pollution…
Gold mine with cyanide
leach piles and ponds in
South Dakota

4. Earth’s geological processes
Geology - study of earth’s processes
Planet made up of core, mantle, and
crust
Solid, HOT
Semi-solid
Solid rock,
mostly

5. Mantle has top layer called
asthenosphere - like silly putty
This flows and pulls on the crust

6. Crust is very thin - called lithosphere
Oceanic crust
Continental crust

7. Crust made up of pieces called tectonic
plates
– Move slowly - about the rate your fingernails
grow
– Geologic activity mostly at plate boundaries
Earthquakes, volcanoes, etc

8. Plate move away from each other =
divergent plates
– Magma flows up through the cracks
– Creates oceanic ridges

9. Plates move toward each other =
convergent plates
– Denser oceanic plate forced under lighter
continental crust - called subduction
– A trench forms here and mountains are
built up

10. Plates slide past each other =
transform fault
– Cause earthquakes
– Most in ocean
– San Andreas fault in CA

11. Weathering and erosion
These processes
break down the
earth
– Wind
– Water
– Glaciers

12. Volcanoes
At subduction zones
Kills people, wipes out habitat and
animals
Leaves behind beautiful mountains,
lakes, enriches the soil
Mt. St. Helens in WA before & after Crater Lake in OR

13. Earthquakes
Occur along faults
Measured on the Richter scale - a log
scale

14. Tsunamis
Series of huge waves caused by a
sudden drop or rise in the sea floor

15. An area of Indonesia before the tsunami

16. and after…

17. The Rock Cycle
Crust is minerals and rocks
– Minerals like NaCl (salt) and Au (gold)
– Rocks are solid combos of minerals (quartz)
3 kinds of rock:
– Igneous rock - cooled, hardened magma
Granite, lava rock
– Sedimentary rock - made of compressed sediment
Sandstone, shale, limestone
– Metamorphic rock - when existing rock is subjected to
tremendous heat/pressure that changes its properties
Slate, marble

18. SLOW
Concentrates
nonrenewable
mineral
resources
essential to life

19. Mineral Resources
Mineral resource = a
concentration of a mineral
in the crust that can be
harvested and made into
useful products
Nonrenewable resource
Examples:
– Metallic minerals - coal,
iron, copper
– Nonmetallic minerals -
sand, limestone

20. Ore - rock with a good concentration of
a desirable mineral in it
– High grade ore - lots
– Low grade ore - less
High grade
gold ore

21. examples
 Aluminum - packaging,
building
 Steel - an alloy of iron
for building, computers,
cars, oil drilling bits,
pipelines
 Platinum - electrical
equipment
 Gold - electrical
equipment, jewelry,
coins, medical implants
 Sand - glass, bricks,
concrete
 Gravel - roads,
cement
 Phosphates -
fertilizers,
detergents

22. Harvesting minerals takes TONS of
energy and generates a lot of pollution
Harvesting minerals creates TONS of
jobs and generates income
Biggest issue: environmentalBiggest issue: environmental
damagedamage
– High grade ore - get good bang for buck
– Low grade ore - use more energy &
cause more damage to get less

23. Harvesting mineral resources
 Surface mining - for minerals near the surface; 90%
of non-fuel resources in USA obtained this way
– Heavy machinery strips away overburden - the soil and rock
on top of the mineral deposit
This is discarded as spoils
– Gold from streams - forests cleared for equipment & land
dredged up from river bottom is left on land - called tailings

24. Types of
surface
mining
 Open-pit mining -
machines dig holes and
remove ore
 Strip mining - good for
deposits that lay in long
strips
 Area strip mining - on
flat land, whole areas
cleared
 Contour strip mining -
for hills
 Mountain top removal -
just what it sounds like!

25. Subsurface mining
For coal and metals deep underground
Dig deep vertical shafts
Blast open tunnels and chambers to
reach deposit
Chilean miners
trapped in copper
mine for 69 days
in 2010

26. Effects of mining on the planet
 Scars/damages the earth
 Spoils/tailings erode away
 Spoils/tailings dumped into waterways
and other areas
 Loss of topsoil means plants can’t
regrow there easily
 Toxic chemicals (arsenic, mercury)
used to process orehttp://appvoices.org/

27. http://minerals.usgs.gov/minerals/pubs/mapd

28. Mining in developing nations
 Small scale
 Usually illegal
 Very destructive
– Hydraulic mining - water
cannons wash away entire
hillsides to harvest gold
– Chemicals and sediment
cause massive pollution
– Workers enslaved or work
under very dangerous
conditions for little or no
money

29. Removing mineral from ore
 Ore mineral - what we want
 Rest of the rock called gangue
 Getting ore out of gangue requires
toxic chemicals and leaves behind
tailings that can blow into other
areas
 Smelting uses heat to extract the
mineral from the ore - produces lots
of air pollution, acidifies soil, leaves
solid and liquid hazardous waste
 Chemical extraction uses cyanide

30. Summitville
Gold Mine
in Colorado
 Canadian
company bought
land from US
gov’t
 Spent $1 million
prepping the
area for mining
 Harvested $98
million in gold
 Declared
bankruptcy,
closed up shop,
and left us with
the mess

31. Clean up
 We can restore land in surface mines but
very expensive ($70 billion just in US)
 Subsurface mining not as damaging but…
– Way more dangerous for workers
– Subsidence

32. Mining waste
 Mining produces 75% of all solid waste in the
US
 Causes major air and water pollution when
wind and water carry chemical laced spoils to
new areas
– 40% of western watersheds polluted from mining
– Mining in US accounts for half of all air pollution
Ohio River

33. How long will our mineral
resources last?
Who has them?
– US, Canada, Russia, South Africa,
Australia supply most of the mineral
resources used in the world
– US, Germany, Russia use 75% of the
minerals but have just 8% of the
population

34. Depletion of mineral resources
 Economic depletion - so little
left it is no longer worth it to
harvest it
– Then we must recycle/reuse, use
less, find a substitute, or do without
 Depletion time - the time it takes
to use up 80% of the reserves at
a given rate of use
– Depends on recycle rates, new
discoveries of reserves, prices, etc

36. US General Mining Law of
1872
http://news.nationalgeographic.com/news/20