Rocks and minerals and their exploitation Flashcards
Define rock
The solid and naturally occurring material composed of minerals that forms the Earth’s outer layer, or crust.
2 types of igneous rocks+ Formation
Plutonic/ Intrusive: Cooling and crystallization of magma (molten rocks found in the mantle below Earth’s surface) within the crust
Volcanic/ Extrusive: Solidification of lava (molten rock that reaches the surface through volcanos or fissures) on the surface
Formation of sedimentary rocks
- Rocks cracked and broken through weathering (e.g. freeze-thaw action)
- These sediments are then transported to new locations by erosion
- Skeletons, sediments, sand, silt etc. build up into thick layers at the bottom of the sea
- As new layers are added, the bottom ones are compressed into strata of hard rock (Cementation)
Formation of metamorphic rocks
Igneous and sedimentary rocks are heated and put under great pressure by Earth’s movements. This causes a chemical change in their minerals which forms metamorphic rocks.
Example of each type of rock
Igneous-
Intrusive: Granite
Extrusive: Basalt
Sedimentary-
Limestone (Calcium carbonate)
Sandstone (Sand, clay)
Shale (Silt, clay)
Metamorphic-
Shale–> Slate
Limestone –> Marble
Uses of rocks
- Furniture (M)
- Statue/Ornaments/Decoration (M)
- Building Material (S)
- Writing (chalk)
Describe the rock cycle
Through lithification, sediments become sedimentary rocks. After getting heated and put under pressure these rocks become metamorphic. The metamorphic rocks can get weathered and moved into becoming sediments which repeats the process. Or, the metamorphic rocks can melt to turn into magma which cools and crystalises into an igneous rock. This igenous rock can get put under pressure and heated turning it into a metamorphic rock or it gets weathered, eroded and deposited forming into a sedimentary rock again.
Difference between surface and sub-surface mining
Surface (open pit/cast) -
Can only be used when rocks and minerals are close to the surface and surrounding area is not heavily built up
The soil and rock overlying the ore body is remove by machinery
Then excavators dig out and remove the ore body from benches that circle the mine at descending levels
Sub-surface-
Uses methods like declines or shafts to remove underground mineral
The overlying rock remains in place but the ore is hauled to the surface in huge trucks or tunnels are sunk down adjacent to the ore body which is removed by lifts
How can you determine whether there are ore bodies?
- Mineral ‘greenfield’ exploration
- Detecting radiation
- Measuring magnetism
- Remote sensing sattelite imagery
Economic factors that need to be taken into account:
- Environmental Impact Assessment
- Amount of ore present underground
- The demand for the element
- Locations suitability
- The ore grade
- Financial support
Economic impacts of rock and mineral extraction
- Multiplier effect- jobs due to the mine
- Trickledown effect- jobs due to the miners
- Government receives money from property taxes which is used to increase standard of living
(only +)
Social impacts of rock and mineral extraction (-+3)
+
1. Better paid work- standards of living increase
2. New infrastructure of transport, water supply built for mines
3. Cheap or free access to mine facilities such as its school, hospital
4. Social community development projects paid for by the mine
-
1. Sudden rise in disposable income can lead to consumption of alcohol, nuisances and crime
2. People may have to be displaced from their land to make way for the mine
3. Lack of regulation may lead to poor health and safety standards
4. Pollution
Environmental impacts of rock and mineral extraction
- Habitat and biodiversity loss
- Water pollution- chemicals
- Air pollution- crushing of minerals
- Visual and noise pollution
Define
- Remediation
- Reuse
- Restoration
- Making sure the site is made safe
- Using the decommissioned site for another purpose
- Rebuilding the ecosystem
Remediation
- Site is made safe by removing machinery, disposing waste
- Waste rock is covered in top soil and planted out with vegetation
- Tailings mixed with water and disposed of in tailings ponds
- Bioremediation to treat contaminated water (prokaryotes degrade contaminants in soil)
