Introduction to Minerals: Mining
Read the following passage and:
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Highlight THREE examples of minerals
Circle THREE types of mining
Underline THREE disadvantages (CONS) to mining
Minerals are nonliving, naturally occurring chemical compounds. Each mineral contains
a different combination of elements, with atoms arranged to form a solid, crystalline
substance. The practice of finding and extracting minerals from the ground is called mining.
Examples of minerals mined for their economic value are barite, which is used in paper and
paint, and gypsum, which is used in compressed powdered form to make the building material
drywall.
While these and other mineral resources are actively mined in the U.S., no minerals
have a stronger historical tie to Nevada, home of the McCaw School of Mines featured in this
video, than precious metals, especially gold. Gold can be found in two kinds of deposits.
Placer deposits form where sand, gravel, and other materials have been transported by
running water. Lode deposits are mineral-filled cracks, called veins, within quartz rock.
One method of collecting placer gold is called panning. Gold has a high specific
gravity, which means it is denser than water and most other minerals. Thus, gold nuggets of
varying sizes can be easily separated from a surrounding sediment, or matrix, by adding
water. In panning, the dense gold settles at the bottom of a pan, and the matrix gets washed
away. While gold can still be extracted in this manner, most gold is mined using one of two
other methods—surface or underground mining—whereby minerals are extracted from
excavated rock called ore.
Surface mining is used to obtain minerals at or near the surface. Open-pit mines are
found in sandy or gravelly terrain, where the surface material covering a deposit is structurally
unsuitable for tunneling. Using this method, thousands of tons of ore rock can be moved each
day. Because ore rock may contain less than 5/100ths of an ounce of gold per ton of rock,
large debris piles form at open-pit mine sites.
Underground, or subsurface, mining is used when mineral resources are located
further underground. Underground mining involves the building of tunnels and shafts, and
requires scaffolding made of wood or other materials to keep the mine caves structurally safe.
Subsurface mining techniques include strip mining, in which layers of rock and soil overlying a
lode deposit are blasted with explosives and removed before specialized machines are used
to extract the mineral.
Mining can be a highly dangerous and polluting industry. Mineral extraction can also
disturb large areas of Earth's surface, leaving gaping holes in mined areas. In recent years,
regulations have been put in place in the U.S. to help protect both miners and the
environment. Toxic waste products and contaminated water may no longer be dumped onto
adjacent land or waters, and reclamation projects are now required to ensure that land can be
used again after mining.
Introduction to Minerals: Mining
Watch the video clip found at:
http://www.teachersdomain.org/asset/klvx08_vid_klvxminer/
Answer the questions based on the video.
1. Why does gold sink to the bottom when miners "pan" for gold?
Gold is denser than any other item in the pan! Dense things sink.
2. Describe the tools and engineering challenges of making a shaft mine safe for
mineral extraction by miners.
They make square sets to keep the surface from caving in (they support the surface
material).
3. How is gypsum transformed into building materials? Can you name other minerals
that you have in your home that were recovered through mining?
It is ground into a powder and pressed between two pieces of cardboard to create
“sheetrock”, or drywall.
Talc is another example of a mineral used by many people in daily life. Talc is a
very soft mineral (the softest!) and it is ground into a powder (often scented) and
used as a beauty product.
We also use halite (salt) for flavoring foods!
4. Are mined materials renewable or non-renewable resources?
Minerals are renewable in the sense that the rock cycle is an ongoing
process, but the timescale of the rock cycle (millions of years) means that,
during a human lifespan, minerals are essentially considered non-renewable.