Eudialyte Value, Price, and Jewelry Information

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Oval-cut eudialyte, 0.52 cts, 6.4 x 4.7 x 3.0 mm, Mont St. Hilaire, Quebec, Canada. © ARK Rare Gems. Used with permission.

Although lapidaries can cut cabochons and decorative objects from massive or translucent eudialyte crystals, transparent material suitable for faceting is elusive and always small.

Eudialyte Information

Data Value
Name Eudialyte
Colors Shades of brownish red, yellowish brown, reddish orange, orangey pink, pink, red.
Hardness 5-5.5
Fracture Uneven
Cleavage Basal, indistinct
Formula Na4( Ca,Fe,Ce,Mn)2ZrSi6O17(OH,CI)2
Crystallography Hexagonal (trigonal); tabular crystals, may be hexagonal or trigonal; also prismatic, rhombohedral, massive.
Crystallographic Forms
Refractive Index 1.591-1.633
Birefringence 0.003-0.010
Dispersion None
Luminescence Not reported
Luminescence Present No
Absorption Spectrum Not diagnostic
Pleochroism Weak, varies with body color: o = colorless/pink/pale yellow; e = pink to colorless.
Optics = 1.591-1.623; = 1.594-1.633. Uniaxial (+) but sign variable; eucolite reported to be (-).
Optic Sign Uniaxial +, Uniaxial -
Luster Vitreous; greasy; may be dull.
Specific Gravity 2.74-2.98
Transparency Often translucent, rarely transparent.
Etymology From Greek words meaning “easy to dissolve,” because of the mineral’s easy solubility in acids.
Occurrence Nepheline syenites and associated pegmatites.
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eudialyte box - Russia

A box made from carved red eudialyte and black and white matrix (even the feet), 4.50 x 2.75 x 1.50 inches, Kola Peninsula, Murmanskaja Oblast’, Northern Region, Russia. Photo courtesy of and Heritage Auctions.

What is Eudialyte?

Eudialyte, also spelled eudialite or eudyalite, belongs to a mineral group of the same name. Although this group of trigonal cyclosilicates contains many members, eudialytes are the only ones likely to be encountered as gemstones.

Some calcium-rich eudialytes, known as eucolites, have a uniaxial (-) optic character. These may also have higher refractive indices (RI) and specific gravity (SG) values than other eudialytes.

Does Eudialyte Make a Good Jewelry Stone?

eudialyte cabochon

Eudialyte cabochon, 42.65 cts, 30.3 x 34 mm. © The Gem Trader. Used with permission.

With a hardness of 5 to 5.5, eudialyte jewelry stones should have protective settings to shield them from scratches. Occasional use is also advisable.

While uncut eudialyte crystals are popular specimens for mineral collections, faceted gemstones would make very rare, very prized additions.

Eudialytes can have deep to bright red colors, and gem cutters commonly fashion them into cabochons and carved objects.

Lapidaries often carve eudialytes into spheres. These objects frequently highlight the combination of black and white minerals in the matrix, especially black aegirine crystals, which adds a striking contrast to the red eudialyte stone.

Dragon's blood sphere - Russia

This “Dragon’s Blood” eudialyte sphere has an intense carmine red color with green-black aegirine accents. 3” diameter, Khibiny Massif, Kola Peninsula, Murmanskaja Oblast’, Northern Region, Russia. Photo courtesy of and Heritage Auctions.

Are Eudialytes Radioactive?

Eudialytes are mildly radioactive, but wearing or handling pieces under 5 cts (1 gram) should pose no health risks. On the other hand, holding a eudialyte sphere of 5,000 cts (1 kg) — a very large piece, indeed — would expose you to 2.40 mREM per hour. To put that in perspective, the average annual estimated radiation exposure in the U.S. from background radiation, medical sources, and consumer products is 360 mRem.

The radioactivity chart on the Webmineral site can help you estimate exposure for holding different sizes of eudialytes. You can also use a Geiger counter to measure the radioactivity of a specific gem or sample.

eudialytes - Russia

Eudialytes, 4.5 x 3.1 x 2.9 cm, Khibiny Massif, Kola Peninsula, Murmanskaja Oblast’, Northern Region, Russia. © Rob Lavinsky, Used with permission.

Are There Synthetic Eudialytes?

Scientists have synthesized eudialytes for geological and petrological research. However, there is no known jewelry use for this lab-created material. There are no known gemstone treatments or enhancements.

Where are Eudialytes Found?

The most notable source of eudialyte gem material, particularly for cabochons and carvings, is the Kola Peninsula in Russia.

Two localities in Quebec, Canada produce red, facetable eudialytes: Mont St. Hilaire (o = 1.596, e = 1.600; birefringence = 0.004); Kipawa Complex, Sheffield Lake, Temiscamingue County.

Greenland has multiple sites, such as Qaqortoq (Julienhaab District), which produces crystals up to 1” in length.

eudialyte crystals - Greenland

Chocolate (brownish red) eudialytes with aegirine, 6.1 x 5.3 x 4.3 cm, Kangerdluarssuq Firth, Ilimaussaq complex, Narsaq, Kitaa (West Greenland) Province, Greenland. © Rob Lavinsky, Used with permission.

Other notable sources include the following locations:

  • Magnet Cove, Arkansas, United States: rich red color, in feldspar.
  • Sweden: (o = 1.598; e = 1.604; birefringence = 0.004; SG = 2.88)
  • Brazil; Ampasibitika, Madagascar; Pilansberg, South Africa.
eudialyte - Brazil

Eudialyte with alkali feldspar (white), aegirine (black), and biotite (brown), Brazil. Photo by Kevin Walsh. Licensed under CC By 2.0.

Stone Sizes

Lapidaries have faceted eudialytes well under 1 ct from Quebec material. These deep red gems are extremely rare.

  • National Museums of Canada (Ottawa, Ontario): 0.30, 0.40 (intense red, Sheffield Lake, Quebec, Canada).

How to Care for Eudialyte Stones

Although eudialytes smaller than 5 cts are safe to wear, you should still take extra precautions when storing radioactive gems of any size. Keep eudialytes enclosed and separated from other gems, since radiation may gradually alter their color. Over time, even mildly radioactive materials release radon gases. Use radon detectors to monitor the buildup of radon gases in the storage container as well as the room.

To safely store and cut eudialyte, follow the recommendations for radioactive materials in our faceting safety guide.

Eudialytes are soluble in acids. Clean them only with a soft brush, mild detergent, and warm water. Consult our gemstone jewelry cleaning guide for more care recommendations.

eudialyte sphere - Canada

A maroon red eudialyte sphere with patches of black aegirine and white feldspar, 2” in diameter, Canada. Photo courtesy of and Heritage Auctions.

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