Leucite Value, Price, and Jewelry Information

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Faint yellow, brilliant pear-cut leucite, 3.03 cts, 12.2 x 8.5 mm, near Ostia, Italy. © The Gem Trader. Used with permission.

Although abundant in various lava rocks, leucite is extremely rare in gem-quality form and often has a milky or cloudy look. Faceted stones as well as well-shaped crystals are prized by collectors.

Leucite Information

Data Value
Name Leucite
Crystallography Tetragonal (pseudo-cubic). Crystals trapezohedral; granular.
Crystallographic Forms
Refractive Index 1.50
Colors Colorless, white, gray, yellowish. May appear reddish due to impurities.
Luster Vitreous; dull on some crystals.
Hardness 5.5-6
Fracture Conchoidal
Specific Gravity 2.47-2.50
Birefringence Very low to zero.
Cleavage Poor
Dispersion 0.008-0.010
Luminescence Medium-bright orange in LW (Italy) or none. Blueish glow in X-rays.
Luminescence Present Yes
Luminescence Type Fluorescent, UV-Long, X-ray Colors
Transparency Transparent to translucent
Phenomena Some specimens may show color flashes similar to play of color.
Formula KAISi2O6.
Pleochroism None
Optics Isotropic: N ~ 1.50. Some specimens may be doubly refractive. Optically (+) if uniaxial. May be anomalously biaxial.
Optic Sign Uniaxial +
Etymology From the Greek leukos, meaning "white."
Occurrence In potassium-rich basic lavas.
Inclusions Crystals of apatite, augite, magnesite, natural glass, olivine, and spinel.

Does Leucite Make a Good Jewelry Stone?

You’re more likely to find faceted leucites in mineral collections than jewelry collections. Although some stones may have unusual color flashes, their general appearance doesn’t typically lend itself to jewelry wear. They also only have a hardness of 5.5 to 6, which makes them susceptible to scratching from household dust. On the other hand, they have poor cleavage, which actually makes them resistant to splitting. Nevertheless, protective settings are recommended, especially for ring use.

Leucite: Italy (2.4). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Is Leucite a Type of Garnet?

Because of their sometimes white, milky appearance and outwardly isometric shapes, leucites have been called “white garnets.” However, leucite and garnet are distinct gem species with very different refractive indices (RI), specific gravity (SG), and hardness.

Although colorless grossular garnet is called “leuco garnet,” that only means this stone shares an etymology with leucite. Leukos is the Greek word for “white.”

Identifying Characteristics

Leucite crystallizes into an isometric structure at very high temperatures (~900° C). However, as it cools, it recrystallizes into a tetragonal structure while retaining an outwardly isometric shape. Since tetragonal crystals have axes of two different lengths, some leucites have a very weak birefringence. (In contrast, isometric gems are singly refractive). This transformation into a tetragonal structure also frequently causes striation and twinning.

Kaolinite - Brazil

If exposed to the air and other elements, leucite can pseudomorph (change chemistry without changing shape) into pseudoleucite, a combination of orthoclase feldspar and nepheline. Further exposure can transform it into the clay mineral kaolinite, like these specimens from Brazil. Photo by Eurico Zimbres. Licensed under CC By-SA 2.5.

Any leucites over three carats in weight will likely contain inclusions.

Although leucites have weak dispersion (0.008-0.010), some specimens may show an unusually high, colorful “fire.” Their internal twinning and striation may cause this peculiar, “play-of-color” type of effect.

A faint yellow, cushion-cut leucite with a flash of color, 1.51 cts, 8.6 x 7.1 mm, near Ostia, Italy. © The Gem Trader. Used with permission.

Are There Synthetic Leucites?

Scientists have synthesized leucite for geological research. However, there’s no known jewelry use for this lab-created material.

There are no known gemstone treatments for leucites.

Where is Leucite Found?

Although this mineral occurs in many localities all over the world, to date, only Italy has produced transparent, facetable leucite crystals. The Alban Hills near Rome produce transparent, colorless crystals up to about 1 cm in size.

Mount Vesuvius (Monte Somma) is the type locality of this mineral.

Notable sources of fine crystals include the following:

  • United States: Arkansas; Montana; New Jersey; Wyoming.
  • Australia; Brazil; British Columbia, Canada; Democratic Republic of the Congo; France; Germany; Tanzania; Uganda.
large crystal - Arkansas

Large leucite crystal, 5.0 x 4.4 x 4.3 cm, Magnet Cove, Hot Spring County, Arkansas. © Rob Lavinsky, www.iRocks.com. Used with permission.

Stone Sizes

Faceters have cut Italian material to about three carats. This facetable material is scarce, always small, and clean only in very tiny stones.

Caring for Leucites

Use a soft brush, mild detergent, and warm water for cleaning. Consult our gemstone jewelry care guide for more recommendations.

Faceted leucite, 2.15 cts - Italy

Leucite, 2.15 cts, Italy. Photo © Joel E. Arem, PhD, FGA. Used with permission.

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