What is it and
how is it formed? Coal is a
sedimentary rock made up of plants from a million years
ago. First the plants make a layer and then they are pushed
down by layers of plants on top of them. This bottom layer
becomes something called
peat. The layers and layers of
plants that keep piling up on top of the peat make it change
into lignite and then bituminous coal and then anthracite
How and where is it
mined? Coal is mined using
underground mining. The kind of mining that is
used depends on where the coal is found and how close to the
surface it is. If it is only a few feet below the surface,
layers of dirt will be bulldozed off and then a kind of
surface mining will be used. If engineers see that there is
coal deep down in the Earth, they will decide if it will
cost too much to bring it up. If they decide that the
mining company can make lots of money by mining it, they
will choose an underground method that goes along with the
land that is mined. For example: An engineer finds a
of coal that runs out the side of a hill. This would mean
that they probably wouldn’t use a
shaft mine that is dug
straight down from the top of the hill, but would probably
slope mine that goes in from the hill side. The
shaft mine would mean more digging to reach the coal than
the slope mine would have. With mine owners, the most
important thing is to make money while keeping the mining
costs [like electricity, hours the men work, insurance,
etc.] down. Coal is mined all over the world.
What is it
used for? Coal is used in
plastic, papermaking, heat, perfume, rubber, charcoal,
roofing shingles, glassmaking, and iron and steel.
There are three main kinds of coal that are used for
heat. Lignite is brown, breaks easily, and smokes when it is burned.
It has 30 percent carbon in it. Bituminous coal is a soft coal that is
black. It doesn’t shine very much when light is shined on it.
When it is burned, it is almost smokeless. Anthracite is the hardest
coal and burns the best of all three. It is black and shiny.
Coal is the biggest
energy resource in the U.S. It is found in layers that are called beds
seams. The picture
above is a coal seam.