Where does NaCl come from?

How do they make table salt? One person told me they boil sea water, but this doesn’t make sense to me. There are other things in sea water other table salt, and to boil that much of it would cost a lot of money. Another person told me it comes from mines, but I doubt this fro similar reasons.

it is mined underground.

Salt ponds.

And salt is mined though I’m not sure if that’s for table use.


sea salt is from evaporated seawater.

salt from mines is purified through dissolving and recrystallization multiple times.

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.

The amount of solid salt underground is staggering. This includes layers of salt underneath rock layers under the sea. As noted above, they are the results of ancient seas evaporating, and later being covered in other strata. Such salt layers can be many hundreds of feet thick. If you are away from a coast and find such a deposit not too far down, you have a very economic source of salt.

The other thing to note is that salt for human consumption is a minuscule portion of the use of salt production.

One should also note that evaporating seawater is not done by boiling the water (except maybe for any salt produced as a by-product of distillation desalination plants). Rather it is evaporated by solar heat, typically in wide shallow salt pans.

What about Kosher salt? Also, is Kosher salt really kosher (i.e. prayed over by a rabbi, etc)?

Kosher salt is a bit of a misnomer. It’s not really kosher as opposed to non-kosher (all salt is really kosher to eat), it’s called that because it’s used in the koshering process for meat. It’s more accurately called “koshering salt.”

The difference from normal table salt is that the crystals are bigger and flatter and are better at covering meat.

Not necessarily underground, some salt mines are open-air. This is the most common source for table salt in the US (I used to work for Norton, the “umbrella girl” company).

As for man-made salt ponds, they are the most common form in other regions, such as near the Mediterranean basin. There is evidence of such operations from pre-Christian times (for example in the town of Vigo, in NW Spain).

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.

You mean Morton?

Yeah, those. Oopsies! Can I blame the antivirus?

Were you the umbrella girl?

Here’s a video of salt being mined. I know it’s a bit dated, but it looks pretty much identical to Dirty Jobs episode on salt mines from a few years ago.

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).

As for boiling sea water - yes, that too has a long tradition. Coastal areas in the Meditterrean do it, but some South American countries have inland salt lakes. I’ll tell you a secret: boiling it doesn’t cost any money for us Europeans, because as socalists we have our own fusion generator during daylight for free. It does take a little more time - several weeks - than putting a little immersion heater into each basin, but it doesn’t cost anything. With each basin, the salt is concentrated more. There are also several grades of salt - the top that is skimmed off with skill while there’s still water left is called Fleur de Sel (Flower of Salt) and sells for a high price, while the coarse salt at the end of the process is cheaper.

As for additional stuff besides pure NaCl in the salt: these are minute traces. Iodine needs to be added.
If you were thinking of all the dirt and oil in todays oceans: things are inspected and regulated, and the places in Spain and France and so on have been doing this for some time, so they know they have to watch their money-making industry from pollution.
Some people in the natural food branch want specific salt from the Himalayas because it has special ingredients and is more pure than the conventionally manufactured salt - but that’s just money-grabbing with mis-information, they could as well buy normal rock salt.

There’s a whole recent book on this, worth reading. Most salt is dug out of underground deposits (both table salt and road salt). A moderate amount is made by using sunlight to evaporate seawater; this is almost all table salt, as it ranges from slightly more expensive than mined salt to wildly expensive gourmet salts with exotic colors and crystal shapes.

At times in history, fires were indeed used to evaporate seawater to get salt – not just attempts but serious industries. Not used much if at all now because mining is much cheaper.
You do get slight amounts of other minerals besides 100% pure NaCl; whether mined or evaporated it all comes from seawater. Generally the other minerals are not enough to worry about. Some fancy evaporated salts have enough of the local sand to make them pink or dark grey or whatever. And most ordinary table salt has iodine added as a health supplement (because at one point in the last hundred years or so it was discovered that a lot of diets were deficient in iodine, and salt was the easiest way to get iodine widely distributed).

Nah, she’s several decades older than me.

Wow, I didn’t know we built that one using EU-funds! Bad constanze! :smiley:

Hey I said we have it, I didn’t say we built it!

But if we’re going to spend that EU money somewhere like Greece, we might as well get something out of it, don’t you think? And us northerns would like our own fusion reactor - several sizes smaller, sure, but a bit more summer …mmmmmm.

Not only that, but also – Kosher has nothing to to with being “prayed over by a rabbi.”

The OP should take a look at Mark Kurlansky’s Salt. It’s an excellent book.


As an aside, the history of Venice and the salt trade is really interesting stuff.