Earth’s Structure, Rocks, Minerals, and Industrial Uses
Earth’s Structure
At the center is the hot core, surrounded by the mantle (molten rock). The outer part of the mantle is the source of magma that reaches the surface. The crust is the most important layer for people and is made up of seven large tectonic plates.
Types of Rock (Formation)
- Igneous rocks: ‘Formed by fire’ and associated with volcanic activity. Granite and basalt are the most common types.
- Granite: Formed from magma forced into rocks during the formation of fold mountains.
- Basalt: Formed from lava that pours out of volcanoes.
- Sedimentary rocks: Made of sediments (small particles of rock broken off from other rocks).
- Sandstone: Consists of grains of sand.
- Clay: Forms from the accumulation and compression of deposits of mud.
- Metamorphic rocks: Changed by heat and pressure within the Earth’s crust.
Distribution, Types, and Reserves of Major Minerals
A mineral is a substance obtained by mining.
- Metallic
- Ferrous: (Iron)
- Non-ferrous: (Copper)
- Precious: (Gold, silver)
Found in very old igneous rocks and young fold mountains.
- Non-metallic
- For industry: (Salt)
- Farming: (Potash)
- Energy supplies: (Oil)
- Precious gemstones: (Diamonds)
Mineral Reserves
A reserve is a known source of a mineral that has not yet been mined.
Common minerals will last for hundreds of years, but others are expected to run out more quickly.
Search and Extraction
Open-Cast Mining
Deep Mining
- Clear vegetation and remove topsoil.
- Break up rock with explosives.
- Remove loose rock.
- Tip the rock into trucks.
- Sink a vertical shaft down to where the minerals are.
- Make a horizontal tunnel.
- Extract the minerals.
- Bring the loose rock up.
- Bring the minerals to the surface.
Deep mining is dangerous, with potential problems like falling roofs, flooding, gas, and fires.
Open-cast mining is cheaper because no large machines are needed, and it is safer because miners are closer to the surface.
Rocks and Minerals in Industrial Processes
Some rocks are in demand for construction and road building. Nearly all igneous and metamorphic rocks (hard rocks) can be used directly as building stone. Rocks that are abundant and low in value tend to be used near the areas where they outcrop.
Examples:
- Chalk (cement)
- Gravel (concrete)
- Clay (bricks and pottery)
- Sand (glass)
Limestone has many uses. It is the raw material for cement and concrete. It acts as a cleaner and is harder than many other sedimentary rocks.
Steel has been replaced by aluminum or plastics in some applications. Aluminum is lighter and less liable to corrosion, making it suitable for aircraft manufacture, but steel is stronger.
Potash is known as a fertilizer but can also be used in the manufacture of explosives, glass, paper, etc.
Industrial Revolution
The Industrial Revolution was based upon coal as the fuel and iron ore as the raw material for steel. Without iron, industrial growth and economic development would not have been possible.
The invention of the steam engine revolutionized industry and transport. Goods were made in factories using machinery operated by engines. Railways and iron ships were invented. These inventions increased the human need for energy and reduced human dependence on natural sources. It also led to urbanization and the growth of cities as people moved out of rural areas.