Metal Ores

o Minerals are important as a source of metals and other materials needed by our society.

o Ores are naturally occurring rocks that contain metal or metal compounds (minerals) in sufficient amounts to make it worthwhile extracting them.

o Some minerals, such as iron ore, have to be treated before they can be used.

o While there is a huge amount of mineral wealth in the Earth’s crust, the amount is finite.

o No new mineral resources are created to replace what we take from the ground — at least, not in humanity’s lifetime.

Mining

• Ores are materials that contain a high proportion of a useful mineral.

• Rocks contain a great variety of useful minerals. Mining and quarrying involve blasting, drilling, and digging up rocks to extract the minerals. Most mines and quarries are worked for building materials, coal, metal ores, and gem-rich rocks and deposits. Mining is noisy, dusty, and can require the use of dangerous chemicals, all of which can cause environmental damage.

• Aluminium is not found as solid sheets in the ground. It is part of the ore called bauxite, which is made of aluminium, oxygen and iron.

• Most of the made objects we use every day are manufactured from materials that come from the Earth. These are all non-renewable resources and include minerals, metals and fossil fuels.

• The process of extracting useful minerals from the Earth is known as mining. A few metals, such as gold, are found in a pure state. Mostly they are found in combination with other substances and need to be separated before they can be used.

Examples of Ores

Ore is a deposit in the Earth’s crust of one or more valuable minerals. The most valuable ore deposits contain metals crucial to industry and trade, like copper, gold, and iron.

• Copper ore is mined for a variety of industrial uses. Copper, an excellent conductor of electricity, is used as electrical wire. Copper is also used in construction. It is a common material in pipes and plumbing material.

• Like copper, gold is also mined for industry. For example, space helmets are plated with a thin layer of gold to protect astronauts eyes from harmful solar radiation. However, most gold is used to create jewelry. For thousands of years, gold ore was mined as a basis for currency, or money. Most nations stopped valuing their money on the gold standard in the twentieth century.

• Iron ore has been mined for thousands of years. Iron, the second-most abundant metal on Earth, is the main component of steel. Steel is a strong, valuable building material. Iron is used in everything from glass to fertilizerto the solid rocket boosters needed for the space shuttle to leave the Earths atmosphere.

Metals are often associated with particular ores. Aluminum, for example, is usually found in the ore called bauxite. Aluminum found in bauxite is used in containers, cosmetics, and medicines.

UNDERGROUND MINING

A gold mine in Indonesia is an example of an underground mine, where rock is dug out by machinery deep under the surface. There are two main types of underground mine: shaft mines, which are normally deep, with vertical shafts leading to tunnels; and drift mines, which are near the surface. Underground mining is very dangerous because of possible flooding, explosive gases, and falling rocks.

OPENCAST MINING

At the Bingham copper mine in Utah, USA, the ore deposit is close to the surface and is extracted by opencast mining. Opencast mining is cheaper and easier than underground mining because no shafts have to be dug, but it does more damage to the landscape. Once the ore is dug up, it is carried away by trucks, railway, or conveyor belts.

Coal

Most of Australia’s energy used to produce electricity comes from coal. In New South Wales, most electricity is generated by power stations in the Hunter Valley, using coal.

Natural Gas

Natural gas is a mixture of hydrocarbons (chemicals made up of hydrogen and carbon atoms), and mainly contains the gases methane, ethane, butane and propane. A source of natural gas is called a gas field rather than a mine. The gas is extracted and separated into its different gases, then piped to cities and towns for various uses in homes or burnt in power stations to generate electricity. Australia has rich deposits of methane gas inside coal beds. This gas is called coal seam gas (CSG) and is the purest form of natural gas. The CSG industry in Australia is relatively well established and currently provides 90% of Queensland’s gas. It has been estimated that Australia has enough CSG to power a city of five million people for 1000 years!

Crude Oil

Crude oil, also known as petroleum, is a thick black liquid that is separated into various products including petrol, diesel, aviation fuel and kerosene. The largest sources of petroleum (oil and gas combined) in Australia are in Bass Strait and off the north-western coast.