|Where does salt come from?|
|Question Date: 2017-03-02|
Salt is sodium chloride NaCl. It forms in
saline lakes and in marine environments where
there is a LOT of evaporation of water.
So, the analogy is, sprinkle salt into a few table
spoons of water; not too much. Make sure the salt
crystals all dissolve, then take this salty water
and put it on a dish and let the water evaporate.
When you come back you will see a crusty white
substance... that is halite (NaCl) table
salt. Same thing happens in nature in arid
environments like in and around the Red Sea and
other salt water lagoons in hot dry places.
There are many types of "salt", and they generally
form in the same way. "Salts" are part of a
group of minerals called "evaporites", meaning
they form from evaporation of water. The most
common salt we think of today is known as
"table salt" -- the salt you put on your
food -- and is usually formed from evaporating
seawater (called "sea salt").
This kind of salt is actually a mineral called
halite (pronounced, hey-light), and is made of
sodium-chloride (NaCl). Because our oceans
have lots of dissolved sodium (Na), salt can
easily form out of drying seawater. When a pool
(or pond) of seawater is stagnant for a while, it
allows the sunlight to heat the water. As the
water evaporates, it leaves behind the sodium (and
other elements, like chlorine). When enough water
has evaporated, sodium and chlorine like to bond
together to form solid halite (salt).
People have also produced salt from natural
spring water in big evaporation pools. These
evaporation pools will form salt by allowing water
to evaporate, which leaves behind sodium and
chlorine (just like evaporating ocean water to
form sea salt). Humans have "harvested" salt from
the ocean and from spring waters for thousands of
There are also deposits of salt within rocks,
which can be "mined" and then used. These
deposits of salt in rocks, however, were also
formed in the same process as modern salt.
Most salt comes from the evaporation of water
saturated with the elements sodium and
chlorine. Sometimes it contains salt from
ancient seas which dried up, and sometimes the
salt forms from the drying of saline lakes like
the Aral Sea in Central Asia.
The salt we use doesn't always come from modern
seas. For instance, much of Utah and western
Colorado contains layers of salt thousands of feet
thick buried under layers of sediment. The
hidden salt formed from a large shallow sea which
concentrated sodium and chlorine from the
weathering of mountain ranges which covered
Colorado and Utah.
Because salt is so soft, it moves really easily
and can pierce through other rock units. Regions
in Iran actually contain salt glaciers which can
flow over the landscape. This occurs because the
region is too arid for rain to dissolve the salt.
Chemically, salt is the combination of a sodium
ion and a chlorine ion. Sodium ion, Na+, has a
positive charge on it. The chlorine ion, Cl-, has
a negative charge on it. This makes them attracted
to each other. Additionally, Cl- has an incomplete
octet, and a valence election from Na+ fills that
octet, making the pair much more stable and happy.
In a solution of NaCl, the water will
eventually evaporate off, forming tiny crystals
with a cube like shape, this is called table
salt, and it’s what you taste and use on your
french fries and other various dishes!
Geographically, salt comes from all around
us. Some salt is found underground formed
from dried up ancient seas, and some has
even arrived from outer space in the form of
meteors! Our biggest source of salt is of
course, our ocean. Deep shaft mining,
solution mining, or solar evaporation are all
methods used to extract salt from our external
environment. China is the biggest salt
producer, followed closely by the US. If we
were to extract all of the salt in the sea at this
exact moment, it would cover the world’s total
land mass to a depth of 35 METERS!
Salt is a mineral, so we mine it from the
earth. There are many kinds of salt, but the
kind of salt that we eat on fries is just one
variety of salt that we mine from the earth. The
scientific name for this kind of salt is
halite. When geologists are testing rock
for minerals, the best way to check for salt is
actually to lick the rock!
When rocks contain a large amount of a valuable
mineral, we call this a "deposit". There
are some very large salt deposits in the United
States, China and Canada. We mine these (get
it out from the ground), purify them (remove any
unwanted substances so the salt pure) and then
Salt is a mineral - actually many minerals, but
themost common salt on Earth is sodium chloride
(NaCl). Different salts are composed of
Sodium chloride salt dissolves readily in
water, which is why the oceans are full of
it. Commercial salt is either taken from the
sea with the water evaporated off or is mined in
salt mines, which are themselves the result of
saltwater lakes that dried up leaving the salt
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