Sunrise over the Dead Sea. Sunrise over the Dead Sea. Sunrise over the Dead Sea reveals a large bank of solid salt deposits. (Photo: Ievgen Sosnytski / Shutterstock)

How does Dead Sea salt form those giant cubes?

Geology and chemistry come together to explain this natural phenomenon.

The Dead Sea between Israel and Jordan is known for its saltiness — at about 34 percent salinity, it's almost 10 times saltier than the Pacific Ocean. That hypersalinity is what makes it so much fun to swim there, since the extra salt makes people more buoyant, resulting in many Instagram shots of floating fun. But the salt that's left behind when the Dead Sea's water evaporates enchants and delights people as well. It collects into all kinds of unusual solids, from undulating formations reminiscent of modern sculpture, to what look like giant smooth drapes on the sandy shore, to others that form into perfect cubes of various sizes.

How does salty water become perfect little boxes of translucence? It seems almost miraculous, but, as it turns out, that's actually the default setting.

Sea salt forms naturally when sodium (Na) and chlorine (Cl) atoms come out of solution via evaporation (see the reverse effect in the video explainer below).

As the water dissipates via drying, the NaCl molecules arrange themselves in a repeating pattern of positive and negative ions to form a crystal structure — this particular structure results in a flat-sided cube based on the shape underlying bonds.

Dr. Mark T. Ford, a mineralogist at Texas A&M University in Kingsville, Texas, explained to From The Grapevine: "The cubic shape is a direct result of how the Na and Cl atoms are stacked together. The atoms are different sizes and when stacked together in an orderly fashion, the resultant shape is a cube. Thus, as the mineral grows, it also takes this form."

The resultant mineral, halite, will always have a cuboidal structure, whether it's teeny-tiny (think table salt) or extra-large, like some of the salt found at the shores of the Dead Sea (see exactly how big in the video below).

"Dead Sea salt crystals get so large because of the high concentrations of sodium and chlorine atoms in the lake. Generally speaking, the more atoms available to add to the crystalline structure, the larger and faster the mineral can grow," said Ford.

But not all the salt found at the Dead Sea is in perfect little cubes — what about the rest of it, that forms in so many other strange and interesting shapes?

All kinds of other compounds and minerals make their way into salt, sometimes disrupting the molecular structure enough so it no longer forms cubes. "Sometimes in a crystalline structure other atoms can substitute for one another. For example, a potassium (K) or magnesium (Mg) atom can substitute for a sodium (Na) atom," said Ford.

These impurities can also lend flavors to edible salts. The basic NaCl will always look and act — and taste — the same, but the presence of other minerals is the reason a dash of Himalayan salt or Mediterranean sea salt might be more pleasing to your palate.


Photos and SlideshowsPhotos and Slideshows
How does Dead Sea salt form those giant cubes?
Geology and chemistry come together to explain this natural phenomenon.