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Pink Halite Hopper Crystals
HALIDES · ISOMETRIC

Halite

NaCl

Hardness
2–2.5
Streak
White
Spec. Gravity
2.1–2.6
System
Isometric

About

Halite, the natural form of salt, is a very common and well-known mineral. It is found in solid masses, and as a dissolved solution in the oceans and in salt lakes. The inland lakes that are rich in salt exist in arid regions, and may also be below sea level without an outlet. These lakes evaporate during dry seasons, causing a recession in the water level and an increase of salinity content. When this happens, salt forms on the evaporated shores of the lake. This also happens as the tributaries of salt lakes are diverted for human and agricultural use, causing the lake to dry up with additional salt forming at the evaporating shoreline. Many of these inland lakes have already dried up, leaving over enormous salt deposits which may be commercially mined.

Halite also exists in non-arid regions, in underground deposits which can reach great depths. Underground Halite deposits are often mined by drilling wells into the salt layer, and bringing in hot water which quickly dissolves the salt into a brine. The brine is saturated with dissolved salt and is then pumped out. The brine evaporates and the remainder salt crystallizes and is harvested. Most commercially available Rock Salt is regrown from evaporated salt brine and is not the original natural crystals. Halite also forms from evaporation at salt springs where saline water comes out of the ground in a salt deposit and precipitates as rounded globular masses.

In some underground salt deposits such as Texas and Louisiana, salt is pushed upwards by an underground force through soft ground and forms arched structures known as salt domes. These deposits are also important sources of salt mining operations and are very unique geological formations.

Although the color range of Halite can be caused by impurities, the deep blue and violet colors are actually caused by defects within the crystal lattice, and the pink and peach colors of many dry lake Halite specimens are caused by bacteria from various algae.

Artificial Halite can easily be grown as crystals by allowing a saturated saltwater solution to evaporate. Hopper-shaped cubes may result as the brine evaporates and the crystal grows. A few Halite specimens on the market are actually artificially grown crystals formed in this manner.

Crystal Forms & Aggregates

Other ID Marks

1) Salty taste.
2) Soluble in water, especially warm water.
3) Some specimens fluoresce, usually red.

Striking Features

Salty taste, softness, and crystal formations

Environment

Varieties

✓ common  · ✗ uncommon

  • Hydrohalite— Hydrohalite is not really a variety of Halite, but a very rare, similar mineral. Its chemical formula is "NaCl · 2H2O", which is in essence Halite containing water. It forms only under very unique conditions where the water does not dissolve the salt. When the salt in sea water or saline spring water in very cold climates crystallizes, it forms together with Ice which has no dissolving effect on salt. The ice forms an integral part of the structure of the mineral, and causes the mineral to be stable.
  • Rock Salt— Rock Salt may be a synonym of the mineral Halite, but is also used referring to a rock composed of 95 to 99 percent Halite, containing impurities such as the minerals Anhydrite, Gypsum, Dolomite, Quartz, and Pyrite.

Uses

Halite is the source of common salt. Enormous Halite deposits are worked for the mining of salt. Salt has many uses, and must be heavily mined to satisfy demand. Some of its most common uses are as food seasoning, for road safety to melt snow and ice, as salt licks for cattle (these provide the cattle with salt, which is essential to their health), and for medicinal purposes. Halite is also the most important ore of the elements sodium and chlorine.

Noteworthy Localities

Halite comes from numerous localities, and enormous salt mines exist throughout the world. However, good specimens are remarkably less common considering the vast salt deposits. Perfect cubes on a matrix have once come from Salzburg, Austria, and fine crystals, especially remarkably blue crystals, have come from the salt deposits of Stassfurt, Hessen, Germany. Poland has many prolific salt mines, some of which have been around for hundreds of years and have produced specimens. These include Inowroclaw, Lubin, Wieliczka, and Klodawa. Other classic European localities are Racalmuto, Agrigento, Sicily, Italy; and Mulhouse, Alsace, France, where it occurs as fibrous veins.

The Dead Sea in Israel and Jordan is slowly evaporating and its shoreline continuously receding. This has been causing very interesting Halite growths and crystals to form at the water's edge. An enormous salt flat which produces very large white Halite crystals is Salar de Uyuni, Bolivia.

In the U.S., enormous underground deposits exist in the states of New York, Michigan, Ohio, Kansas, Oklahoma, Texas, and Louisiana, where the salt is commercially mined. The cities of Detroit, Michigan, and Cleveland, Ohio, both have productive Halite mines directly beneath the city.

Fine Halite crystals in above ground deposits are generally restricted to arid regions, usually dry lakes or saline lakes. The most important locality for collector specimens is Trona and Searles Lake, San Bernardino Co., California. Other important regions in California are the dry lakes of Kern Co.; the Salton Sea (Riverside and Imperial Counties); Death Valley, Inyo Co.; Bristol Dry Lake, near Amboy, San Bernardino Co.; and Soda Lake, San Luis Obispo Co. There are many other important salt lake deposits in the U.S. and throughout the world where crystallized Halite cane be found, but special mention should be also be made to the dry Lake Bonneville and the Great Salt Lake, Utah.

Deep blue and occasionally purple crystals, including those with color zoning, have come from the potash mines in the Carlsbad area, Eddy Co., New Mexico. Especially of note are the outstanding royal blue crystals that have recently come from the Intrepid Potash East Mine in that district.

Common Mineral Associations

Distinguishing Similar Minerals

The strong salty taste combined with its crystal formations will distinguish Halite from all other minerals.

Photos

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Crystal forms

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