What is it and where is it formed?
Halite is salt that is
sedimentary. All salt comes from the sea in some way.
If salt is found on land, it is because there was once a sea
there that disappeared, leaving the salt behind. If it is in
hard layers underground, it is called rock salt.
How and where is it mined? In smaller bodies of salt
water, evaporation will make a vapor that rises. Then the salt in the water
will form crystals and fall back into the water. When this happens over and
over, a bed of salt is made. Salt is mined in different ways depending on where
it is found or even made. For the salt that is found where seas used to be,
underground mining can be used. The miners will use normal mining methods like
the ones in hard rock mining to do this. Room-and-pillar mining is done. This
is where the tunnels are divided into rooms by man-made pillars of salt [like
the pillars of coal in a coal mine]. Tunnels are dug, holes drilled, and big
blocks of rock salt are taken out just like they do with coal. A good thing
about mining rock salt is that there isn’t any water or gas in the mines.
Electric shovels put the salt into trailers to take it to a crushing machine.
In some mines, the crushing and screening are done before it is brought out of
the mine. Since salt will dissolve in water, sometimes solution mining is
done. Solution mining is where a
shaft is dug down into the rock salt. Hot
water is forced down into the shaft where it dissolves the salt walls around
it. This forms a brine. [To see what a brine looks like, mix about 1/8 cup of
salt in 1 cup of warm water. Stir until it is dissolved. You won’t be able to
see through it. This is a brine.] The brine is pumped to the surface and then
the water evaporates from it, leaving the salt. In other places where salt is
found, miners will just scrape salt layers off of the bottom of lakes [salt
lakes]. A third of the salt in the U.S. comes from hard rock mining, one half
from solution mining, and the rest from separating the salt from sea water and
dried up lakes. Once it is taken out of the ground, it is separated according
to what it will be used for and then crushed and sorted by size. The best salt
becomes table salt and is mixed with other minerals to keep it from clumping
up. Salt is mined in the United States, China, Germany, India, and Canada. Most
of the United States' salt comes from Louisiana, Texas, and New York.
What is it used for? Salt is necessary for people and
animals to have in their diets. It is used in the food industry and as rock
salt to melt snow on roads. It is used to help keep food for long amounts of
time, in ceramics, soap, nuclear reactors, medicine, water softeners, and animal
Years ago it was used as money. Workers were paid in salt
and people traded for it. If you were “worth your salt”, you were worth the
money you were being paid.
If rock salt beds move, they
will push salt into underground piles called domes.