Where does NaCl come from?

[mnemosyne]

One of my favourite trips when I was in Europe as a kid was to the Salzburgmines. So beautiful, with that awesome slide down towards the underground lake and the little trains to make it that much cooler!

If you ever have the opportunity to visit these mines, or ones like it, I highly recommend it!

[Hari_Seldon]

One more point about kosher salt. Although all salt is kosher for most uses, apparently some salt has added dextrose (presumably to keep it free flowing) and that is made from corn, which makes it unsuitable during passover (when all grains are banned unless…well I won’t go into that, but basically they should never have contacted water).

[Kansas_Beekeeper]

If you are ever in Hutchinson, KS, you can see for yourself:

http://www.undergroundmuseum.org/index.php

[WotNot]

@Nava

According to one of my college teachers (Inorganic Chem), there were attempts at obtaining salt by boiling seawater during the 19th century, but they didn’t last long: the salt thus obtained would easily stain unapettizing green or yellow. The culprit, always according to him, was the use of copper cauldrons - the cod salted using that salt would have been poisonous due to copper contamination.

Sea salt was obtained by boiling here on the North East coast of England since the middle ages, and was a sizeable industry up till around 1800. Unlike some of our continental neighbours, we couldn’t rely on free fusion power for evaporation, but we did have a ready supply of coal. Around here, the pans were made of iron.

Apparently the brine was clarified with the blood of sheep and black cattle – presumably that would have been decidedly non-kosher salt.

[MikeS]

Salt is indeed mined. It’s also a bad idea to drill into a salt mine from the lake above.

[silenus]

Avery Island, Louisiana, home of Tabasco Pepper Sauce is situated on top of a rather large salt dome. That’s where they mine the salt for their sauce, and selling the salt has kept the company afloat during lean times back just after the Civil War.

There are salt mines in Poland that are so old the miners have carved whole cathedrals out of salt hundreds of meters below the surface.

[Ignatz]

Syracuse, NY sits on a huge salt bed with mines going for miles under Lake Erie.

http://www.saltworks.us/salt_info/si_HistoryOfSalt.asp

[Chronos]

There are also salt mines under the lake in Cleveland.

[Darth_Panda]

Oh, and lest we forget:

How did salt and pepper become the standard table spices?

Is sea salt better for you than regular salt? Why does salt enhance the...

[Spectre_of_Pithecanthropus]

@constanze

Why do you doubt two people who give you real information? Have they previously given you wrong information?
Are you still in the process of education, or did you finish school? Because if you’ve never heard of the history of salt, I would think your education lacking (or you didn’t pay attention).

Salt in mountain mines is the result of geologic processes, and has been mined for centuries there. Before the Romans, centuries. The Romans actually paid their soldiers partly in salt, hence the word salary. Because salt is not only important for the human diet, before fridges it was one of the few ways of preserving meat (and with pickling, also veggies).

I am familiar with most of these facts, but I don’t recall anyone teaching them to me; I must have read them somewhere or other.

However, I am a little surprised to learn of the importance of underground mining in this. I would have thought that salt, as a commodity, isn’t valuable enough to justify all the expenses entailed by the heavy machinery, mining engineers, etc. Though I was aware of some famous salt mines here and there, I thought most of it was obtained through the evaporation of seawater, or collected from the surface of dry alkaline “lakes” like we have in California.

[Digital_is_the_new_Analog]

Bonaire makes salt via evaporation. The ponds/lakes/etc are interesting. Very colorful.
-D/a

[Acsenray]

I would have thought that salt, as a commodity, isn’t valuable enough to justify all the expenses entailed by the heavy machinery, mining engineers, etc.

Again, read Kurlansky’s Salt. Salt is one of the most important substances to human civilization.

[Chronos]

However, I am a little surprised to learn of the importance of underground mining in this. I would have thought that salt, as a commodity, isn’t valuable enough to justify all the expenses entailed by the heavy machinery, mining engineers, etc.

One thing it has going for it is that it’s a lot easier to mine than most minerals. Most minerals, you get thin veins of useful ore mixed in with a lot of rock, but with salt mines, pretty much the entire volume is salt. And it’s easier to cut than most rocks.

[copperwindow]

@johnpost

sea salt is from evaporated seawater.

Then why aren’t there other salts (like KCl) in table salt?

[fumster]

@copperwindow

Then why aren’t there other salts (like KCl) in table salt?

Sea salt and table salt are two different things. Table salt is refined to be almost pure NaCl. Sea salt will have traces of other minerals and salts.

[Anaglyph]

@Chronos

One thing it has going for it is that it’s a lot easier to mine than most minerals. Most minerals, you get thin veins of useful ore mixed in with a lot of rock, but with salt mines, pretty much the entire volume is salt. And it’s easier to cut than most rocks.

In places where rock salt is located far from the surface, water is pumped into the salt-bearing layer, dissolves the salt and the brine is pumped up and the salt extracted.

[Snarky_Kong]

@Chronos

And the salt in the underground mines ultimately comes from seas that dried up long ago. So you could say it’s all sea salt.

And seas become salty from dissolved rocks. The ciiiiiiircle of life.

[Little_Nemo]

@Anaglyph

In places where rock salt is located far from the surface, water is pumped into the salt-bearing layer, dissolves the salt and the brine is pumped up and the salt extracted.

That can be a problem though. The water will dissolve all the salt and that can make the entire mine collapse. Digging allows them to leave support pillars.

[Bill_Door]

@Hari_Seldon

One more point about kosher salt. Although all salt is kosher for most uses, apparently some salt has added dextrose (presumably to keep it free flowing) and that is made from corn, which makes it unsuitable during passover (when all grains are banned unless…well I won’t go into that, but basically they should never have contacted water).

The dextrose is added to stabilize the iodine. Morton’s says

“In 1924 Morton became the first company to produce iodized salt for the table in order to reduce the incidence of simple goiter. Dextrose is added to stabilize the iodide. Iodine is vital to the proper functioning of the thyroid gland and the prevention of goiter. Actually, the amount of dextrose in salt is so small that it is dietetically insignificant. Morton® Iodized Table Salt contains 0.04 percent dextrose or 40 milligrams per 100 grams of salt. Morton® Plain Table Salt contains neither iodine nor dextrose. All Morton Salt products containing potassium iodide are labeled as such.”

[Canadjun]

@copperwindow

Then why aren’t there other salts (like KCl) in table salt?

Others have mentioned that table salt is purified. However, keep in mind as well that there is a lot more NaCl than KCl in seawater.