Chapter 1: Rocks and Minerals Flashcards
Igneous rock formation and types
Plutonic/ intrusive- Solidification of magma inside volcano, slow process, large crystals = granite
Volcanic/ extrusive- Solidification of lava outside, quick due to atmospheric pressure, small crystals, easy to extract = basalt
Sedimentary rocks
sediments of rocks, fossils, clay, silt, sand, gravel, small boulders
weathering and erosion leads to sedimentation of these particles accumulated in layers
as time passes, gets compressed due to pressure of built up layers over them
compaction (physical) and cementation (chemical)
form hard rock due to pressure as lithification - sedimentary rock
limestone, sandstone, shale
Metamorphic rock
earths movement causes existing rocks heated and put under pressure to cause chemical or physical changes in minerals in rocks to form new rock
marble (limestone) , slate (shale)
Rock cycle
igneous –>weathering and erosion–> sediment –>compaction, cementation and lithification –> sedimentary –> heat and pressure –> metamorphic –> melting –> magma –> crystallisation –> igneous
all rocks –> weathering and erosion –> sediments –> compaction, cementation and lithification –> sedimentary rock
all rocks –> heat and pressure –> metamorphic rock
all rocks –> melting –> magma –> crystallisation –> igneous rock
Surface mining
Rocks containing minerals found close to surface
Open cast / open pit/ open cut/ strip
Overburden (topsoil) removed
Cheaper machinery
Larger deposits
Subsurface mining
Rocks are underground
declines, vertical or inclined shafts , tunnels
deep / shaft mining
more complex
expensive machinery
dangerous as roofs may collapse
Factors affecting decision for extraction
exploration
geology
geological difficulties resulting in investment- if rocks underground, subsurface requires more money
accessibility
locations suitability for mining- not remote, not too close to settlements
environmental impact assessment- costs of meeting requirements (pollution, compensating citizens)
supply and demand
scarcity and likely long term demand for element for profit
Methods of surveying
Radiation detection (satellite)
Variations in magnetic field
Remote sensing (aerial photography)
Satellite images (confirm presence of minerals)
Economic Impacts
Job opportunities
Government gets tax to improve quality of life
Improve living standards
Improve local economy
Environmental impacts
Loss of habitat
Noise / water / air / land / visual pollution
Soil erosion (cause sedimentation in rivers)
Social impacts
improved living standards
new infrastructure and transport
cheap or free access to schools hospitals etc
subsidised housing
drug and alcohol abuse
conflicts
displacement
poor health and safety
pollution
Managing impact of extraction
Remediation
Restoration
Reuse
Remediation
Safe disposal of mining waste
(remove machinery, drain pipelines, dispose hazardous waste)
Bioremediation
treat water contamination
prokaryotes degrade contaminated elements from soil and water
Restoration
Rebuilding ecosystems and visual scenery
(natural reserves, lakes)
soil improvement
afforestation
Reuse
Reusing equipment, transportation lines, infrastructure, landfill site
Ecotourism (recreation)
