Where Does Salt Come From?

Step 1 of 5

The sea leaves, the salt cannot.

Warm a bowl of seawater and the water floats off as vapour. Salt has no way of doing that, so it is left sitting on the bottom in little cubes — which is all a salt pan is, done at the size of a field.

Step 2 of 5

Some seas dried up long ago.

Where an ancient sea evaporated, it left a bed of salt that later got buried under rock. Salt mines are those beds — you are digging in the floor of a sea that vanished millions of years ago.

Some salt mines are so dry that footprints and tool marks left by miners centuries ago are still perfectly sharp.

Step 3 of 5

The crystals are little cubes.

Tip salt onto dark paper and look closely. Every grain is a cube, because the two kinds of atom inside stack in a strict alternating grid — and a grid like that can only break into boxes.

Step 4 of 5

It preserves food by drying it out.

Before fridges, salt was how food was kept. Salt pulls water out of anything it touches, and the bacteria that spoil food cannot live without water — so salted fish and meat simply keep.

Step 5 of 5

You need it, but not much.

Your nerves and muscles will not work without salt, and you lose it in sweat. But the amount you actually need is small, and most food that comes in a packet already has plenty.