Chapter 1 - Rocks and minerals and their exploitation Flashcards
What does the rock cycle show?
The rock cycle shows the changes between the three rock types (igneous, sedimentary and metamorphic) and the processes causing these changes.
The rock cycle diagram
How do igneous rocks form?
Igneous rocks form when molten cools to form solid rock. Extrusive igneous rocks occur if the rock cools quickly, forming small crystals e.g. basalt.
Intrusive igneous rocks occur is the rock cools slowly, forming large crystals e.g. granite.
What are two examples of igneous rocks?
Examples of igneous rocks are granite and basalt.
How do sedimentary rocks form?
Sedimentary rocks form by the weathering and erosion of existing rocks at the earth’s surface. This sediment accumulates into layers and gets pressurized due to the newer deposits above them, forming sedimentary rocks. Fossils may be present in sedimentary rocks.
What are three examples of sedimentary rocks?
Examples of sedimentary rocks are limestone, sandstone, and shale.
How do metamorphic rocks form?
Metamorphic rocks form when existing rocks are put under extreme heat and/or pressure which causes changes in the rock crystal without melting the rock. These changes can be physical, chemical or both.
What are two examples of metamorphic rocks?
Examples of metamorphic rocks are marble and slate.
What are the five methods of exploration?
Prospecting, remote sensing, satellite signals, geochemical analysis/field surveys and geophysics.
What is prospecting?
Prospecting is the process of searching for minerals by examining the surface of rocks
What is remote sensing?
Remote sensing is the process in which information is gathered about the earth’s surface from above. Photographs of the area are taken from the air and these images are carefully analysed for mineral presence. Aerial photography can cover more ground that a person on a surface.
What are satellite signals?
Satellite signals send signals to earth’s surface and collect the reflected signals, indicating the presence of minerals. The unique radiation pattern is processed and analysed by computers. The system works in all weather conditions. The GPS gives the exact location. Large areas can be covered in a low cost. This is the most efficient method.
What is geochemical analysis/field surveys?
Geochemical analysis and field surveys analyse the chemical properties of rocks by taking samples. The samples can be taken from stream sediments, soil, or rocks using shallow drilling. The location of the sample can be accurately found using GPS.
What is geophysics?
Geophysics is a method to identify mineral ores in rocks using their physical properties. A sense of vibrations are sent through earth’s surface. Several sensors and placed at different distances from the source of vibrations on the surface. The vibrations create shock waves that travel down into the rock layers which are then reflected to the sensors on the surface. The shock waves record different patterns depending on the minerals present in the rock layers.
What are the six methods of extraction?
Surface mining, open pit mining, strip mining, subsurface mining, deep mining and shaft mining
What are some examples of surface mining?
Surface mining includes open cast (open pit, open cut) and strip mining.
Describe the process of open pit mining
Open pit mining is used when a valuable deposit is located near the surface. The vegetation is cleared, and the topsoil is removed, the rocks are broken up and loosened by explosives. The loose rock is removed using diggers and the rock or mineral is tipped into trucks or railway wagons and carried away. Building materials such as sand, gravel and stone are removed from open pits called quarries. The topsoil can be placed back onto the mine if the mine closes.
Describe the process of strip mining
Strip mining is used to mine a seam of a mineral. The overburden is removed as a thin strip. This type of mining is mainly used for coal and lignite.
What are some examples of subsurface mining?
Subsurface mining include deep and shaft mining.
Describe the process of deep/shaft mining
Deep and shaft mining is when a vertical shaft is dug into the rock layer containing minerals. A horizontal tunnel is made, following the mineral layer. The mineral is extracted by machines or miners and the loose rock is brought up from the mine and piled up on waste heaps on the surface. The minerals are brought to the surface and transported in trucks or trains. This type of mining is mainly used to gold and diamonds.
What are the four factors that affect the decision to extract rocks and minerals?
Geology, accessibility, environmental impact assessment and supply/demand
How does geology affect the decision to extract rocks and minerals?
High grade ores yield more of the required chemical elements than low grade ores. Small deposits of high-grade ores and worth mining but small deposits of low-grade ores that cannot be mined at a profit are left.
How does accessibility affect the decision to extract rocks and minerals?
Transporting the ore from mine to processing plants can be difficult and expensive. The cost of building road or rail links to the processing plant or the nearest export port must be considered. Carrying out some processing at the mine reduces transport costs. The mining company must be given a license before extracting a deposit. A long-term agreement between the government and mining companies must be reached to avoid rapid rises in the tax which would make mining unprofitable.
How does the environmental impact assessment affect the decision to extract rocks and minerals?
For the license application to be approved, the company must have a plan to keep the loss of the habitat minimal, followed by the restoration of the land and the completion of mining. The choice of site for mine waste should also be considered.
How does supply and demand affect the decision to extract rocks and minerals?
The relation between how much of a commodity is available and how much is needed or wanted by the consumers. An increase in the world demand for any mineral ore will increase the price. The profit from a working mine depends on the changes in supply and demand. If the demand is too high, mines that were not profitable before becoming worth mining. If the demand falls, working mines may lose due to transport and extraction expenses.
What are the eleven impacts of rock and mineral extraction?
Loss of habitat, noise pollution, water pollution, land population, air pollution, visual pollution, employment opportunities, economic impacts, improvements in facilities and infrastructure, improvements to transport, improvements in education and healthcare
Describe loss of habitat as an impact of rock and mineral extraction
Loss of habitat as the vegetation is cleared so plants do not have a place to grow, therefore the animals depending on them for food and shelter are affected.
Describe noise pollution as an impact of rock and mineral extraction
Noise pollution due to machinery and explosives which disturbs the behaviour of animal species and can cause hearing problems for people.
Describe water pollution as an impact of rock and mineral extraction
Water pollution as water supplies may also be polluted, making the water unsafe for people to drink. The water may become acidic and dissolve toxic metal ions. This combination can kill many aquatic organisms. Bioaccumulation is when organisms absorb and retain the ions in their body to the point where it reaches a higher concentration than in the water. Biomagnification is when the concentrations increase higher up the food chain and cause the death of the top consumers.
Suggest how bioremediation can be used to restore this mine (4)
add microbes / bacteria / fungi / microorganisms
add organic matter ;
add soil;
plant seeds/vegetation/trees ;
introduce (grazing) animals ;
State three factors that the company must consider before deciding to extract the uranium (3)
size of deposits ;
accessibility of the deposits / depth of deposit ;
stated environmental impact of mine: e.g., waste disposal / transport impact / habitat destruction / loss of
biodiversity / ease of restoration ;
stated human impact / health implications e.g. radiation risk / cancer ;
cost (extraction) ;
value of the uranium / profitability ;
government licences ;
availability of, labour / machinery ;
public opposition;
Suggest how the mine will affect people living in a nearby village (4)
water pollution ;
noise / visual / air / soil pollution from stated source ;
fear over, radioactive sources / contamination ;
village may need to be relocated ;
employment opportunities ;
improvement in local economy ;
improvement in national economy / increased tax revenue for government ;
improvement in infrastructure / healthcare / schools ;
loss of recreational areas for village ;
Put the processes in the correct order for the formation of sedimentary rock (3)
transport, deposition, sedimentation, compaction, cementation
Suggest reasons why the government does not allow the mining company to extract the minerals at location A (2)
too close to village;
deforestation required / loss of habitat;
mining will cause visual/noise/air pollution;
people would need to be relocated;
Suggest reasons why the mining company decides not to extract the minerals at location B (2)
can’t use open-pit / have to use subsurface / shaft so will be more difficult / subsurface mining is expensive;
small amount of reserve available;
topographically less accessible;
geology;
location / depth of the reserves;
cost effectiveness of extraction;
safety - qualified;
Use the photograph to describe how this land has been restored (2)
land has been filled;
lake / pond, has been made;
car park / new road has been built;
(top)soil added:
trees / vegetation has been planted;
area has been landscaped;
park created;
