Willemite Gemstone: Properties, Meanings, Value & More

With its showstopping, fluorescent green hues, willemite resembles more a glowstick than a gemstone!

Is willemite a rare mineral? This gem isn’t particularly rare, but high-quality specimens can sometimes be hard to come by.

Uncover the secrets behind willemite’s glow as we explore this fluorescent beauty’s properties, history, symbolism, pricing, and more in our Willemite Gemstone Guide.

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

About Willemite Stone

Willemite was named after William I, King of the Netherlands, honoring his contributions to mineralogy and geology.

What is the other name for willemite? That depends on its properties and geographic location. While "willemite" is most common, the mining industry and historical references have bestowed a few alternative pseudonyms, such as:

• Troostite: Honoring American mineralogist Frederick L. Troost, who first identified willemite in N. America

• Green Zinc Ore: Used mainly in the mining industry, referencing willemite’s use as a zinc ore

• Silicocalcite: Sometimes describes willemite due to its composition, including both silica and calcium

• Bologna Stone: Historical name for green fluorescent willemite found near Bologna, Italy

• Moresnetite: Sometimes used for willemite from the Moresnet mines in present-day Belgium, where the mineral was first discovered

Scientists have synthesized willemite for research, particularly to study its luminescence, but synthetic willemite isn’t used in jewelry-making.

While not a traditional zodiac stone, some crystal healers say willemite supports the Gemini in astrology.

So, how do you identify willemite? Its mineral traits can give you some clues.

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

Willemite Specifications & Characteristics

First, is willemite a mineral or rock? If you guessed the former, you’d be right!

Willemite belongs to the silicates mineral family, specifically nesosilicates. Nesosilicates are characterized by isolated silicate tetrahedra (building blocks of silicates) that aren’t linked together by other ions.

In willemite’s crystal system, each silicon atom bonds to four oxygen atoms in a tetrahedral arrangement, with no other ions present. This isolation gives nesosilicates, like willemite, exceptional properties, allowing them to take on various shapes and textures, unlike other minerals.

Is willemite an oxide ore? Nope! As we briefly mentioned earlier, willemite has been used as a less popular zinc ore — but more on that later.

This mineral’s fame comes from its striking green fluorescence, but why does willemite glow? It’s all thanks to trace amounts of manganese in its crystal structure. When UV light hits willemite, the manganese ions absorb the light’s energy, becoming excited. As they release this excess energy, they emit visible light in the green part of the spectrum.

The result? Willemite’s bright green glow.

Does willemite glow in the dark? Willemite won’t glow in the dark without a UV light source to excite its manganese ions first. Once the UV light source is gone, willemite’s fluorescence gradually fades as the ions lose energy.

Here’s an overview of willemite’s mineral traits:

Chemical formula: Zn2(SiO4)

Mohs hardness: 5.5

Color: White, grayish-pink or blue, reddish-brown, yellow, green, black; colorless

Crystal structure: Trigonal

Luster: Vitreous to resinous

Transparency: Transparent to translucent to opaque

Refractive index: 1.69 to 1.72

Density: 3.89 to 4.19

Cleavage: Poor

Fracture: Uneven

Tenacity: Brittle

Streak: White

Luminescence: Fluorescent and phosphorescent (Intense to yellow-green in SW/LW UV; Rarely, non-fluorescence occurs)

Pleochroism: Present, often strong; Usually yellowish-green.

Moving on, let’s peer into willemite’s intriguing past.

Image credit: thisisbossi, Flickr

Willemite History

French mineralogist Serve-Dieu Abailard "Armand" Lévy discovered the semi-precious gemstone in 1830 on former Dutch soil (present-day Belgium).

Ancient Egyptians used willemite to make decorative objects like jewelry, amulets, and figurines. It was particularly valued for its bright green color and association with the god Osiris, often depicted wearing green clothing.

In ancient China, willemite was used to create glazes and pigments for ceramics. It was often combined with other minerals to create unique colors and effects — a practice still used today.

Willemite was once used as a source of zinc for producing brass, bronze, and other alloys. It was vital during World War II when zinc was in high demand for making ammunition and other military equipment.

Today, however, its uses as a zinc ore are mostly retired. This is because other zinc ores, like sphalerite and hemimorphite, are more abundant and easier to mine.

Metaphysically, what is willemite used for?

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

Willemite Healing Properties

Beyond its aesthetic appeal, you can use willemite as a powerful healing stone for balancing your physical and emotional wellness.

Physical Healing

Willemite is thought to produce a sense of overall physical well-being, supporting your body's natural processes and helping it function at its best.

Some of its purported physical benefits include:

• Boosting the immune system

• Regulating your metabolism

• Enhancing vitality

• Promoting healthy sleep

Emotional Healing

Many associate willemite with promoting emotional balance and stability, helping to calm the mind and reduce feelings of stress and anxiety.

Purportedly, willemite uses its energy to enhance the very essence of who you are. In other words, wearing willemite may amplify your individual personality's unique qualities and traits.

Pictured above: Smithsonite and willemite crystal | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Willemite Gemstone Properties

Gemstone grading involves assessing a stone's quality and value based on color, clarity, cut, and carat weight.

Experts appraise willemite according to these exact specifications.

Color

When willemite isn’t emitting its captivating glow, its colors range from pinkish-gray, yellowish-orange, brownish-green, and colorless to a rare blue and pinkish-red variety. But, despite their color, their bright fluorescence is the most sought-after.

Some willemites may also display a weak cat's eye (or chatoyant) effect.

Cut

Faceted willemite is extremely rare, as the stone's fragile nature makes it difficult to use in jewelry. You're more likely to find faceted or cabbed gems in mineral collections than in jewelry collections.

Instead, you’ll usually find willemite sold in its raw (uncut) form. While more affordable, these specimens present equally exquisite properties that many collectors prefer.

Clarity

Willemite is commonly included with calcite, franklinite, zincite, or rhodonite.

Sometimes, willemite exhibits an inclusion pattern known as “herringbone,” resulting from the alignment of its crystal lattice structure.

While more transparent willemite with fewer inclusions is typically more valuable, some inclusions (especially in desirable patterns) add value to the stone.

Carat Weight

Willemite’s size and weight vary widely depending on the source and individual stone.

Faceted and cabochon-cut willemites are typically smaller, most falling within 1 to 5 carats.

Larger stones are considered rare and valuable, with those over 10 carats being especially prized.

Pictured above: Willemite and mimetite specimen | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Willemite Formation & Sources

Willemite occurs in various geological settings but is primarily associated with zinc ore deposits undergoing metamorphism or metasomatism.

Typically, willemite forms from altering zinc-rich rocks and minerals by fluids rich in silica; or hydrothermal activity associated with hot, mineral-rich liquids moving through rock formations.

Globally, where can you find willemite?

Mining Locations

It’s said that if you mention willemite to any collector, they’ll likely think of Franklin-Sterling Hill, New Jersey — the only locale where it’s the primary zinc ore.

Other notable sources for willemite are:

• Algeria

• Belgium

• Democratic Republic of the Congo

• Greenland

• Mexico

• Namibia

• Quebec

• United States (AZ, CA, NM, UT)

• Zambia

Curious to know how much willemite costs?

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

Willemite Price & Value

Here’s a quick rundown of what you can expect to pay for different types of willemite:

• Faceted: Rare and highly valued, faceted willemite can fetch anywhere from $50 to $200 per carat, depending on the color, clarity, and size. Stones with a bright, intense green fluorescence are typically the most valuable.

• Cabochons: While less valuable than faceted cuts, cabochon-style willemite can still be quite valuable, ranging anywhere between $10 to $50 per carat. Similar to faceted cuts, cabs exhibiting the best fluorescence and chatoyancy are typically more valuable.

• Rough: Rough specimens are commonly sold by the gram, with prices ranging from $1 to $5 per gram, depending on size and quality. Larger, high-quality rough willemite can garner higher prices.

Knowing how to care for your gemstones will extend their lifespan and keep them looking their best.

Willemite Care and Maintenance

Is willemite radioactive? Toxic? Safe to handle?

Thankfully, handling willemite has no known risks, but proper care is crucial to preserving its beauty over time.

To clean your willemite, use a soft brush, mild detergent, and warm water. Gently brush away impurities and pat dry with a non-abrasive cloth. Store it in a cool, dry place away from harder gems that could damage your stones.

Avoid your willemite coming into contact with:

• Harsh chemicals

• Extreme temperatures

• Direct sunlight

• Steam and ultrasonic cleaners

And with a hardness of only 5.5, protective settings are a must for preventing scratches.

Pictured above: Willemite, Calcite, and Franklinite | Image credit: Orbital Joe, Flickr

Let Willemite Illuminate Your World!

With its mesmerizing green fluorescence and potent healing powers, willemite is as full of life as it is stunning. Truly a crystal that’s sure to spark conversation and turn heads with its unique properties and captivating appearance — why would you settle for a run-of-the-mill gem when you can light up your collection with the ethereal glow of willemite?

Buy willemite and other fluorescent gemstones today!