unit 15

An ore is a rock that contains enough metal to make it worthwhile (economically) to extract it.

Bauxite gives aluminum, chalcopyrite gives copper, galena gives lead, hematite gives iron, and sphalerite gives zinc.

Oxygen and sulfur are found in compounds with metals in many ores. Hematite and bauxite contain oxygen, while galena, chalcopyrite, and sphalerite contain sulfur.

They are all metal-bearing minerals found in ores. Hematite is iron oxide, magnetite is also an iron oxide, and pyrite is iron sulfide and is not commonly considered an ore of iron.

A mineral deposit is a mass of ore that is economically profitable to mine.

A vein deposit is a narrow band of ore (often less than a metre wide) running through rock. A lode deposit is when there are many veins.

Most diamonds are found in disseminated deposits. Kimberlite pipes are formed by deep-origin volcanoes.

Most iron deposits formed 2 billion years ago when life began photosynthesizing and producing oxygen in large quantities. Iron in water reacted with the oxygen to form non-soluble iron (III) oxide, which precipitated out.

Deposits near the surface are mined from open-pit mines. Explosives are used to blast away overlying rock layers.

Deeper deposits are mined from underground mines. A vertical shaft is dug down and then horizontal tunnels called levels access the deposit.

Ore is usually initially processed at the mine site. The rock is crushed into powder and a concentrated ore is extracted by a series of processes.

Tailings are the slurry of waste rock left behind after the concentrated ore is extracted. They are still metal-rich and can leach metals into surrounding waterways and increase their acidity.

Smelting is when the concentrated metal ore is heated beyond its melting point and reacted, often with air, to extract the metal. This is not usually done near the mine site.

An aggregate resource is a mineral resource that is not used for its metal content. Examples include sand and gravel.

A quarry is an open-pit mine used to mine aggregates. We quarry sand because high-quartz sand is used to manufacture glass, and higher quartz content makes better glass.

Gypsum is the primary component of plaster, such as drywall. Halite is used as a seasoning and for water softening.

Potash is a potassium chloride mineral that is primarily used as a fertilizer.

Canada is the world's #1 supplier of potash. It comes from the Devonian evaporite formation in the prairies, particularly Saskatchewan.

A fossil fuel is derived from the storage of organic matter in sedimentary rocks and is therefore rich in carbon. The three important fossil fuels are coal, petroleum, and natural gas.

Coal was formed from plant matter that was buried in sediment millions of years ago and then heated.

Lignite is low-grade coal with about 30% carbon. Bituminous coal forms deeper and at higher temperatures. Anthracite forms at the greatest depths and highest temperatures and is about 90% carbon.

Coal mining can be dangerous because underground mines are susceptible to collapse and miners often develop black lung disease. It can also be destructive, as in strip mining or mountaintop removal. Burning coal also releases greenhouse gases and atmospheric contaminants including sulfur oxides and nitrogen oxides.

Strip mining is surface mining where entire strips of overlying material are removed. Mountaintop removal is like strip mining on steroids, where the topography of the area is flattened.

Coal plays an important role in the production of steel, which is an alloy of iron and carbon. Petroleum is refined into products including gasoline, jet fuel, and plastics.

Most oil and gas is derived primarily from marine microorganisms that accumulated within sea-floor sediments. Crude oil and natural gas are derived from organic matter stored in sedimentary layers before it could be oxidized.

Oil sands are deposits where the oil is exposed near the surface and is highly viscous because of microbial changes at the surface. They are important because Alberta's reserves are the largest single reserve of oil in the world.

Oil sands are controversial because extraction requires a lot of heat and gas, causes strip-mining and tailings ponds, and can release contaminants into groundwater and rivers.

Shale gas is gas trapped within rock that is too impermeable for the gas to escape under normal conditions. It is extracted by hydraulic fracturing, or fracking, using water and chemicals under extremely high pressure.

Fracking is controversial because of the volume of water used, because some jurisdictions do not require disclosure of the chemicals used, and because there is a risk of contaminating water-supply reservoirs.

It is a burning natural gas field collapsed into a cavern, found in Turkmenistan. It has been burning since 1971.