mining and using minerals

thinking critically

  1. What are some disadvantages of underground mining? 6. What is the bottom line when it comes to deciding how what and how to mine? 7. How is land reclaimed after mining? Is it ever fully recovered? 8. How might the history of the Golden State been different if placers had not been found in its rivers?

underground mining

If an ore is deep below Earths surface it may be too expensive to remove all the rock above it. These deposits are taken by underground mining. Underground mines can be very deep. The deepest gold mine in South Africa is more than 3,700 m deep (that is more than 2 miles)! There are various methods of underground mining. Underground mining is more expensive than surface mining. Tunnels must be blasted into the rock so that miners and equipment can get to the ore. Underground mining is dangerous work. Fresh air and lights must be brought in to the tunnels for the miners. The miners breathe in lots of particles and dust while they are underground. The ore is drilled, blasted, or cut away from the surrounding rock and taken out of the tunnels. Sometimes there are explosions as ore is being drilled or blasted. This can lead to a mine collapse. Miners may be hurt or killed in a mining accident.

making metals from minerals

Most minerals are a combination of metal and other elements. The rocks that are taken from a mine are full of valuable minerals plus rock that isnt valuable. This is called waste rock. The valuable minerals must be separated from the waste rock. One way to do this is with a chemical reaction. Chemicals are added to the ores at very high temperatures. For example, getting aluminum from waste rock uses a lot of energy. This is because temperatures greater than 900o C are needed to separate out the aluminum. It also takes a huge amount of electricity. If you recycle just 40 aluminum cans, you will save the energy in one gallon of gasoline. We use over 80 billion cans each year. If all of these cans were recycled, we would save the energy in 2 billion gallons of gasoline!

surface mining

Surface mining is used to obtain mineral ores that are near the surface. Blasting breaks up the soil and rocks that contain the ore. Enormous trucks haul the broken rocks to locations where the ores can be removed. Surface mining includes open-pit mining, quarrying, and strip mining. As the name suggests, open-pit mining creates a big pit from which the ore is mined. Figure 3.22 shows an open-pit diamond mine in Russia. The size of the pit grows as long as the miners can make a profit. Strip mines are similar to open-pit mines, but the ore is removed in large strips. A quarry is a type of open-pit mine that produces rocks and minerals that are used to make buildings and roads.

placer mining

Placer minerals collect in stream gravels. They can be found in modern rivers or ancient riverbeds. California was nicknamed the Golden State. This can be traced back to the discovery of placer gold in 1848. The amount of placer gold brought in miners from around the world. The gold formed in rocks in the Sierra Nevada Mountains. The rocks also contained other valuable minerals. The gold weathered out of the hard rock. It washed downstream and then settled in gravel deposits along the river. Currently, California has active gold and silver mines. California also has mines for non-metal minerals. For example, sand and gravel are mined for construction.

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ore deposits

A mineral deposit that contains enough minerals to be mined for profit is called an ore. Ores are rocks that contain concentrations of valuable minerals. The bauxite shown in the Figure 3.21 is a rock that contains minerals that are used to make aluminum.

finding and mining minerals

Ores have high concentrations of valuable minerals. Certain places on Earth are more likely to have certain ores. Geologists search for the places that might have ore deposits. Some of the valuable deposits may be hidden underground. To find an ore deposit, geologists will go to a likely spot. They then test the physical and chemical properties of soil and rocks. Ore deposits contain valuable minerals. They may also contain other chemical elements that indicate an ore deposit is nearby. After a mineral deposit is found, geologists determine how big it is. They outline the deposit and the surrounding geology on a map. The miners calculate the amount of valuable minerals they think they will get from the deposit. The minerals will only be mined if it is profitable. If it is profitable, they must then decide on the way it should be mined. The two main methods of mining are surface mining and underground mining. Placers are a type of surface deposit.

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mine pollution

Mining can cause pollution. Chemicals released from mining can contaminate nearby water sources. Figure 3.26 shows water that is contaminated from a nearby mine. The United States government has mining standards to protect water quality.

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land reclamation

After the mining is finished, the land is greatly disturbed. The area around the mine needs to be restored to its natural state. This process of restoring the area is called reclamation. Native plants are planted. Pit mines may be refilled or reshaped so that they can become natural areas again. The mining company may be allowed to fill the pit with water to create a lake. The pits may be turned into landfills. Underground mines may be sealed off or left open as homes for bats.

mining and the environment

Mining provides people with many resources they need, but mining can be hazardous to people and the environment. Miners should restore the mined region to its natural state. It is also important to use mineral resources wisely. Most ores are non-renewable resources.

other useful minerals

Metals and gemstones are often shiny, so they catch your eye. Many minerals that we use everyday are not so noticeable. For example, the buildings on your block could not have been built without minerals. The walls in your home might use the mineral gypsum for the sheetrock. The glass in your windows is made from sand, which is mostly the mineral quartz. Talc was once commonly used to make baby powder. The mineral halite is mined for rock salt. Diamond is commonly used in drill bits and saw blades to improve their cutting ability. Copper is used in electrical wiring, and the ore bauxite is the source for the aluminum in your soda can.

uses of ore minerals

We rely on metals, such as aluminum, copper, iron, and gold. Look around the room. How many objects have metal parts? Metals are used in the tiny parts inside your computer, in the wires of anything that uses electricity, and to make the structure of a large building, such as the one shown in the Figure 3.23.

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gemstones and their uses

Some minerals are valuable simply because they are beautiful. Jade has been used for thousands of years in China. Native Americans have been decorating items with turquoise since ancient times. Minerals like jade, turquoise, diamonds, and emeralds are gemstones. A gemstone is a material that is cut and polished to use in jewelry. Many gemstones, such as those shown in Figure 3.24, are minerals. Gemstones are beautiful, rare, and do not break or scratch easily. Generally, rarer gems are more valuable. If a gem Gemstones also have other uses. Most diamonds are actually not used as gemstones. Diamonds are used to cut and polish other materials, such as glass and metals, because they are so hard. The mineral corundum, which makes the gems ruby and sapphire, is used in products like sandpaper. Synthetic rubies and sapphires are also used in lasers.

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instructional diagrams

No diagram descriptions associated with this lesson

questions

Quartz can be found in

a. electrical wiring

b. soda cans

c. sheet rock

-->  d. windows

Which valuable element is found in bauxite ore?

-->  a. aluminum

b. copper

c. corundum

d. iron

What are techniques for finding and deciding whether to use ore?

a. examining chemical elements in the area to determine the presence of ores

b. creating a map of the geology and deposits

c. amounts of ores are calculated to determine profitability

-->  d. all of the above

Which is NOT true of diamonds?

-->  a. more mined diamonds are used for gemstones than for cutting

b. diamonds are often mined underground

c. diamonds can be used to polish other gemstones

d. diamonds are cut to maximize reflecting light

What is NOT true of placer minerals?

a. placer minerals collect in stream gravels

b. placer minerals were found in California in 1848

c. placer minerals are deposited along rivers

-->  d. placer minerals are so small they often are not valuable

Certain places on Earth are more likely than others to have ore deposits.

-->  a. true

b. false

All mines are located deep underground.

a. true

-->  b. false

A placer is a type of underground mineral deposit.

a. true

-->  b. false

Surface mining includes strip mining, open-pit mining, and quarrying.

-->  a. true

b. false

Gold is no longer mined in California.

a. true

-->  b. false

Waste rock is used to make aluminum cans.

a. true

-->  b. false

Underground mining is more expensive than surface mining.

-->  a. true

b. false

Most minerals are a combination of metals and other elements.

-->  a. true

b. false

Rubies are opaque gemstones.

a. true

-->  b. false

Chemical reactions are used to separate minerals from waste rock.

-->  a. true

b. false

Land reclamation is used to restore an area damaged by mining.

-->  a. true

b. false

Minerals must be removed from ore to be useful.

-->  a. true

b. false

It takes more energy to recycle aluminum than to obtain aluminum by mining.

a. true

-->  b. false

Electrical wires are made of the metal copper.

-->  a. true

b. false

Most diamonds are used as gemstones to make jewelry.

a. true

-->  b. false

All the metals we use were originally extracted from the ground as

-->  a. ores.

b. geodes.

c. placers.

d. pure minerals.

Any rock that contains enough minerals to be mined for profit is called a(n)

a. gemstone.

b. vein.

-->  c. ore.

d. none of the above

What is the first step in obtaining minerals?

a. mapping a vein

b. digging a mine

-->  c. locating an ore deposit

d. separating ore from waste rock

Blasting is used to break up rocks in

a. underground mining.

b. open-pit mining.

c. strip mining.

-->  d. all of the above

Which mineral would be obtained from a quarry?

a. gold

b. silver

-->  c. gypsum

d. diamond

Which products are made of minerals?

a. glass

b. rock salt

c. sheetrock

-->  d. all of the above

Placer gold mined in California originally came from the

a. Pacific Ocean.

-->  b. Sierra Nevada Mountains.

c. Mississippi River.

d. Gulf of Mexico.

any rock that contains a concentration of valuable minerals

a. gemstone

b. reclamation

c. quarry

d. surface mining

-->  e. ore

f. bauxite

g. placer

type of open-pit mine that produces rocks and minerals for buildings and roads

a. gemstone

b. reclamation

-->  c. quarry

d. surface mining

e. ore

f. bauxite

g. placer

type of ore that is mined to make aluminum

a. gemstone

b. reclamation

c. quarry

d. surface mining

e. ore

-->  f. bauxite

g. placer

restoring land that was mined to a natural state

a. gemstone

-->  b. reclamation

c. quarry

d. surface mining

e. ore

f. bauxite

g. placer

type of mineral deposit that collects in stream gravel

a. gemstone

b. reclamation

c. quarry

d. surface mining

e. ore

f. bauxite

-->  g. placer

any mineral that is cut and polished and used to make jewelry

-->  a. gemstone

b. reclamation

c. quarry

d. surface mining

e. ore

f. bauxite

g. placer

general name for mining methods that include open-pit mining and strip mining

a. gemstone

b. reclamation

c. quarry

-->  d. surface mining

e. ore

f. bauxite

g. placer

diagram questions

No diagram questions associated with this lesson