Blue Halite

Blue Halite, also known as blue rock salt, is an extremely rare variety of crystallized sodium chloride. It usually occurs in a cubic form but has also been found as masses, grains, and tiny shards. The galactic color spectrum Blue Halite offers is due to minor impurities of potassium within the salt’s chemical composition.

Blue Halite, also known as Blue Halite Crystal or Blue Rock Salt, is a captivating variety of Halite (NaCl) known for its stunning blue color and interesting properties.

The name "halite" comes from the Greek word "hals," meaning "salt."

Formation and Occurrence

Blue halite is primarily found in evaporite deposits, formed from the evaporation of ancient saline lakes or seas. These deposits often contain other minerals, such as anhydrite, gypsum, and potash salts.

The largest deposit of Blue Halite is located in Saskatchewan, Canada, formed during the evaporation of a large ocean that existed around 400 million years ago. Other important localities include deposits in the southern United States, Pakistan, Germany, Spain, Iran, Romania, and the United Kingdom.

Well formed crystal of transparent, rare blue halite from new find.
From: Intrepid Potash East Mine, Carlsbad, New Mexico, USA.
Photo credit: Spirifer Minerals

Blue Halite Properties

Composition: Primarily sodium chloride (NaCl), with trace amounts of other minerals like potassium, calcium, and magnesium contributing to its color.

Color: Primarily blue, ranging from light sky blue to deep indigo, with occasional purple or green hues.

Luster: Vitreous, glassy when polished.

Crystal System: Cubic.

Streak: White.

Hardness: 2.5 on the Mohs scale, easily scratched by most objects.

Cleavage: Three perfect directions, cubic cleavage, forming cubic or rectangular shapes.

Crystal Form: Cubic crystals, often intergrown or massive.

Density: 2.16 g/cm³.

Transparency: Transparent to translucent.

Fracture: Conchoidal.

Specific Gravity: 2.16.

Solubility: Highly soluble in water, readily dissolving in contact.

Magnetism: Non-magnetic.

Fluorescence: Generally inert, but some specimens may exhibit weak fluorescence under ultraviolet light.

Pleochroism: Absent.

Refractive Index: 1.544 - 1.545.

Inclusions: Frequently present, including gas bubbles, fluid inclusions, and other mineral inclusions.

Blue Halite crystals from Kerr McGee Mine, Carlsbad Potash District, Eddy County, New Mexico, USA. Credit: Enchanted Minerals LLC

Where is blue halite found?

Blue halite, a beautiful and rare variety of the mineral halite (rock salt), can be found in a few locations around the world. Here are some of the known sources:

Carlsbad Caverns, New Mexico, USA: The blue halite in Carlsbad Caverns is thought to be caused by natural radiation from nearby sylvite deposits. It can be found in various shades of blue and purple, often with a translucent or even transparent appearance.

Zechstein evaporite basin, Poland: Blue halite crystals have been found in the Kłodawa Salt Mine in Poland. The color is believed to be due to the presence of epigenetic sediments rich in potassium.

Mulhouse Basin, France: This basin is home to a unique variety of fibrous blue halite. The blue color is thought to be caused by organic material trapped within the salt crystals.

Dead Sea, Israel: Blue halite has been reported from the Dead Sea, but it is very rare and difficult to find.

It is important to note that blue halite is a fragile mineral and should be handled with care. It is also soluble in water, so it should not be stored in humid environments.