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Colemanite Gemstone: Properties, Meanings, Value & More

硬硼酸鈣石寶石：屬性、含義、價值等

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Colemanite is a commonly colorless to white mineral known for its various industrial uses and attractive crystals popular among collectors.

How rare is colemanite? The mineral is pretty abundant and even transparent crystals are fairly common.

That said, gemstones aren’t common. Colemanite’s hardness and toughness are low — combined with its heat sensitivity and perfect cleavage, the crystals are hard to cut or keep undamaged if worn in jewelry.

That doesn’t make colemanite any less interesting, though. With a rich history tied to the hottest place on Earth and plenty of fascinating properties, there’s plenty to learn about colemanite!

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

About Colemanite Stone

Colemanite is a semi-precious gemstone that’s usually colorless, gray, or white, though it can also be pale shades of yellow, pink, orange, or brown.

Some synonyms for colemanite are borspar and neocolemanite. In 1911, “neocolemanite” was described as a variety of colemanite found in Los Angeles County, California (USA), that differed from normal colemanite in its crystallographic and optical properties.

What is the common name for colemanite? Industrially, it may be called “calcium borate,” its chemical name.

Speaking of, what is colemanite used for?

Colemanite Uses

One major use of colemanite is as a source of borax. In fact, it was the number-one source of boron until the 1930s after the discovery of kernite. Still, 90 percent of the world’s industrial boron minerals used (as of 2021) are colemanite, kernite, ulexite, and tincal.

Currently, ceramics and glass industries use boron minerals the most. Colemanite is particularly useful for creating heat-resistant glass.

Other significant uses for colemanite and similar boron minerals include:

• Abrasives

• Insecticides

• Fertilizers

• Insulation

• Semiconductors

• Cleaning products (e.g. detergents)

• Steel paints

• Cosmetics

• Pharmaceuticals

• Welding fluxes

• Rocket fuel

Over 75 percent of borate uses are in glass, fertilizers, detergents, and ceramics. Boron detergents are popular for removing stains, softening water, and whitening fabrics.

When used in ceramics, colemanite is a powerful glaze ingredient that acts as a flux, glass-forming agent, and color intensifier.

These days, it may be harder to find good colemanite for glazes. So, what is a substitute for colemanite glazes?

Common colemanite substitutes include Gerstley borate — a combination of colemanite, ulexite, and hectorite — and Cadycal — a cost-effective calcium borate precipitate.

Lastly, scientists have created synthetic colemanite for various research.

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Colemanite Specifications & Characteristics

As a hydrated calcium borate mineral, colemanite’s formula can be written as CaB3O4(OH)3·H2O or Ca2B6O11·5H2O. The first formula is the one approved by the International Mineralogical Association (IMA).

The stone is in the hydrous borate mineral group alongside borax, ulexite, and kernite. More specifically, colemanite is an inoborate like kernite and howlite.

Colemanite crystals may be prismatic, equant, or pseudo-rhombohedral. The mineral can also be nodular, massive and cleavage, granular and compact, or nodular.

At low temperatures, colemanite is pyroelectric and piezoelectric, meaning it becomes electrically charged under heat or mechanical pressure, respectively.

Colemanite properties listed:

• Mohs hardness: 4-4.5

• Color: Colorless, white, gray, yellow, pink, pale amber-orange, brown

• Crystal structure: Monoclinic

• Luster: Vitreous, subadamantine, or adamantine

• Transparency: Transparent to translucent

• Refractive index: 1.586-1.614

• Density: 2.40-2.42

• Cleavage: Perfect on {010}, Distinct/Good on {001}

• Fracture: Irregular/uneven or subconchoidal

• Streak: White

• Luminescence: Fluorescence present - Bright pale yellow in LW-UV & bright pale yellow or white in SW-UV; Sometimes phosphorescence - pale green

• Pleochroism: None

• Birefringence: 0.028-0.030

• Dispersion: Weak

Image credit: DerHexer, Wikimedia Commons, CC-by-sa 4.0

Colemanite History

Colemanite was first discovered in the 1880s near Furnace Creek in Death Valley, a US national park on the California-Nevada border. The first description came from the first California state mineralogist Henry Garber Hanks in 1883.

The name “colemanite” was chosen to honor William Tell Coleman, the owner of the mine where it was discovered. Coleman proposed the name “smithite” first, after his business partner Francis Marion Smith.

Both Coleman and Smith were instrumental in California’s development.

William Tell Coleman

Coleman was a shipping magnate and vigilante group leader in San Francisco starting in 1849.

Shortly after married couple Aaron and Rose Winters discovered borax near Greenland (now Furnace Creek Ranch) in Death Valley in 1881, Coleman established a mining plant, Harmony Borax Works, around 1883. Transporting the mineral out of Death Valley was difficult, with record-high temperatures and no roads or railways.

Ingeniously, Coleman established now-famous twenty mule teams that took the minerals 165 miles to Mojave. His methods were groundbreaking. During operation from 1883 and 1889, these mule teams carried roughly 20 million pounds of borax without losing any mules or wagons.

Francis Marion Smith

Francis Marion Smith was a business magnate and miner nicknamed “The Borax King.” In 1872, he came across a rich borate deposit in Nevada at Teels Marsh.

He staked claims and established the Smith and Storey Brothers Borax Company with his brother — shortened to Smith Bros. Borax Co. and then Teel’s Marsh Borax Company in 1884.

When the Teels Marsh mining slowed down, Smith looked to the Death Valley deposits. In 1890, Coleman went bankrupt, so Smith consolidated Harmony Borax Works and Coleman’s holdings to form the Pacific Coast Borax Company (eventually changed to U.S. Borax).

Smith took some smart branding advice from his advertising manager Stephen Mather (who became first National Parks Service director) by using images of the twenty mule team in a campaign to promote his 20-Mule-Team Borax Soap and register the 20-Mule-Team trademark in 1894.

Overall, Coleman and Smith’s operations put Death Valley on the map, with various media, transportation, and tourism subsequently surrounding the area.

Colemanite Healing Properties

Colemanite is usually a white healing stone, so it joins other white gemstones in possessing cleansing and liberating properties. It’s also a favorite crown chakra stone among energy healers.

Other colemanite metaphysical properties are said to include:

• Broadening your perspective

• Facilitating relaxation

• Strengthening your spiritual connection

• Making you more accepting and patient

Image credit: Dave Dyet, Public Domain

Colemanite Gemstone Properties

Besides rarity, factors affecting colemanite’s value include color, cut, clarity, and carat weight.

Color

Most colemanites are white to gray, but some can be colors like yellow, tan, or amber-orange. Part of its low popularity as a gemstone is because its colors are often pale, so any brighter colors would be rare and valuable.

Cut

Although you can find transparent colemanite crystals, they’re difficult to cut for a few reasons:

Low Mohs hardness

Perfect cleavage

Poor toughness

Heat sensitive

As such, most faceted colemanites are cut for collectors. Some common cuts are emerald, shield, round brilliant, and oval brilliant shapes. The stone’s birefringence may result in facet doubling.

Some colemanite specimens are cut into cabochons. It’s often sold rough (uncut).

Clarity

Clarity is the degree of visible inclusions in a gemstone. Given colemanite’s rarity, visible inclusions aren’t a major factor in its value, but more transparent stones with fewer inclusions may be more desirable.

Carat Weight & Size

By size alone, some colemanite crystals could become 50- to 100-carat gems. However, most are only up to 1 inch.

One unusually large faceted colemanite appeared at the 2022 American Gem Trade Association show: a colorless 7.36-carat gem with a modified traingular brilliant cut.

The Smithsonian Institution has an even larger colorless faceted colemanite that’s 14.85 carats with a round brilliant cut.

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Colemanite Formation & Sources

Colemanite is often a secondary mineral, forming when minerals like priceite, borax, and ulexite are altered by external conditions.

The mineral can also form when dissolved borate compounds are repeatedly deposited by water and the water evaporates, leaving the elements behind to crystallize into colemanite.

What type of rock is colemanite found in? Colemanite minerals are found in evaporite sedimentary rocks at saline lake deposits located in arid environments.

Mining Locations

Where is colemanite found? The best colemanite crystals come from:

• Argentina

• California, USA

• Chile

• Kazakhstan

• Turkey

Other sources include:

• Belarus

• Bolivia

• Canada

• India

• Iran

• Mexico

• Serbia

• Arizona, USA

• Nevada, USA

Want to browse some colemanite for sale? Then let’s go over what prices to expect.

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Colemanite Price & Value

Though rare and pricier than other gems, colemanite is still relatively affordable compared to stones like diamonds or sapphires.

Faceted colemanite gemstones range from around $30 to $530 per carat, with most being under $150 per carat.

The most expensive rough colemanite crystals are generally $200 to $300, but smaller crystals start at $10 each.

Colemanite Care and Maintenance

Last up is gemstone care.

By now, you’ve probably guessed that colemanite requires gentle care. It can be easily scratched and it’s sensitive to heat. Colemanite is also somewhat soluble in water, so avoid soaking them and pat them dry after cleaning (don’t let them air dry).

You can clean colemanite with lukewarm water, mild soap, and a soft toothbrush. Use a soft microfiber cloth to dry it.

You can wear colemanite jewelry occasionally, but it should have protective settings, especially rings.

Store colemanite in a cool, dry environment separate from other gemstones.

Stay Cool and Curious with Colemanite!

It’s ironic that a heat-sensitive stone was discovered in the hottest place on Earth, but colemanite is full of surprises. This uplifting, unique stone is the perfect addition to any collection or healing space!

Buy colemanite and other unique gemstones today!