where does salt come from - Redraw

Understanding the Context

The Natural Sources of Salt

Salt, chemically known as sodium chloride (NaCl), occurs naturally in several forms throughout the Earth’s crust and environment. Understanding where salt comes from begins with exploring its natural geological origins:

1. Sea Salt and Ocean Evaporation

The most familiar source of salt is the world’s oceans. Over millions of years, seawater evaporates under intense sunlight, leaving behind concentrated salt deposits. These deposits accumulate in shallow basins and arid regions where water loss outpaces replenishment—such as salt flats (or salars), coastal plains, and inland lakes.

Key Insights

How does sea salt form?
As evaporated water vanishes, minerals including sodium and chloride ion combine to form crystalline salt. This process occurs naturally in salt flats like the Salar de Uyuni in Bolivia or the Dead Sea basin. Harvesting sea salt typically involves drawing brine into shallow ponds, where sunlight and wind accelerate evaporation.

2. Rock Salt (Halite) from Ancient Seas

Salt is also found in underground rock formations—primarily formed from evaporated seawater trapped millions of years ago. When ancient seas dried up, layers of salt crystals were buried under sediment. Over time, geological pressure transformed these layers into massive salt deposits.

Mining salt:
These underground salt deposits are mined using techniques like block cavern mining or solution mining, where water is injected to dissolve the salt and pump it to the surface. Salt mines in places like Bad Ossia in Italy or Kansas, USA, supply salt for both industrial and culinary uses.

3. Inland Salt Lakes and Salts

Final Thoughts

Not all salt originates from oceans—many lakes in dry climates concentrate salt. When freshwater lakes evaporate in hot, arid regions (e.g., Great Salt Lake in Utah, Lake Asal in Djibouti, or Lake Magadi in Kenya), dissolved minerals, including sodium chloride, precipitate and form salt crusts.

4. Mineral Deposits and Brines

Salt can also be extracted from subterranean brine reservoirs—underground pockets of highly saline water. These brines are often found in mineral-rich regions and are processed through evaporation ponds or chemical extraction to produce table salt and industrial-grade salt.

Industrial and Cultivated Sources of Salt

Modern salt production relies on both natural mining and advanced processing: