Halite Properties, Formula & Mineral Information

Cubic halite crystals — the same geometry as the salt grains on a table — Photo: Zbynek Burival · CC BY-SA 4.0

What is Halite?

Halite is sodium chloride — NaCl — ordinary table salt in mineral form. It crystallizes in cubes, cleaves into cubes, tastes of salt, and dissolves completely in water.

Most halite is an evaporite, left behind when seas and salt lakes dry up. Beds hundreds of meters thick underlie the Gulf Coast, Germany and the Dead Sea basin, and where buried salt is squeezed it rises in slow-motion salt domes that trap oil and gas.

Usually colorless or white, halite turns deep blue or violet where natural radiation rearranges its crystal structure, and pink where salt-loving microbes live inside the grains.

In one sentence: Cubic crystals, cubic cleavage, salty taste, water-soluble — halite may be the easiest mineral on Earth to identify.

Physical Properties

The full data table is in the panel alongside. Here’s what those numbers actually mean.

Taste and solubility. A touch to the tongue gives clean saltiness — and a small crystal dissolves entirely in a drop of water. (Only taste minerals you can already identify with confidence.)

Cubic cleavage. Halite splits perfectly in three directions at right angles, so a crushed crystal yields tiny cubes — exactly the shape of the salt grains on a table.

Softness. Mohs 2.5 — about the hardness of a fingernail.

Color surprises. Radiation from surrounding potash beds creates electron-trapping color centers that turn halite sapphire-blue or violet; the color lives in the structure, not in impurities.

How & Where It Forms

Halite precipitates when salty water evaporates — in today’s salt flats, playas and coastal pans, and in the great evaporite basins of the geologic past. Deep burial makes thick salt flow plastically, bulging upward as salt domes.

Hopper crystals — cubes with stepped, hollowed faces — grow quickly at brine surfaces. Halite also crusts volcanic fumaroles and desert soils.

Often grows alongside:

Sylvite Gypsum Anhydrite Carnallite Thénardite Trona

What It’s Used For

FoodTable salt — seasoning, and humanity’s oldest food preservative.

Road safetyRock salt spread on winter roads lowers water’s freezing point and melts ice.

ChemicalsBrine electrolysis yields chlorine, caustic soda and hydrogen — feedstocks for plastics, soap and PVC.

Water softeningSalt brine regenerates the resin beds inside household water softeners.

How to Identify It

Taste settles it: clean saltiness is halite; a bitter edge suggests its potash partner sylvite. Cubic cleavage and instant solubility in water confirm it. Halite never fizzes in acid (unlike calcite) and is far softer than quartz or fluorite — a fingernail nearly marks it.

Tastes of salt — clean, not bitterDissolves completely in waterPerfect cubic cleavage: crushed grains are tiny cubesSoft — about fingernail hardness (2.5)White streak, glassy luster

Looks like…	But differs because…	Quick test
Sylvite	Its potassium partner — tastes bitter-sharp rather than purely salty and is often reddish	Careful taste test
Calcite	Fizzes in acid, doesn’t dissolve in fresh water, and cleaves into rhombs not cubes	Water drop & acid
Fluorite	Harder (4), cleaves into octahedra, insoluble and tasteless	Taste & cleavage
Quartz	Much harder (7), no cleavage, insoluble	Knife test