Villiaumite Value, Price, and Jewelry Information

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

Villiaumite

Villiaumite is seldom discussed among collectors of rare gemstones because until recently no facetable material was known. The material from Los was reported in 1976 and has been cut into tiny gemstones of deep red color. Despite their small size, they are desirable because so few stones exist. The material from Quebec is larger but very scarce. Villiaumite is somewhat water-soluble, and cutters must use special tricks (such as using alcohol as a cutting coolant) to facet the material.

Villiaumite Information

Data Value
Name Villiaumite
Stone Sizes Los material might yield faceted gems up to 1-2 carats. Gems under 2 carats have been cut from Quebec material.  Smithsonian Institution (Washington, D.C): 1.2 (orange—red).  Private Collection: 12.1 (red, Quebec, cabochon?).
Formula NaF
Colors Deep carmine-red, lavender pink to light orange; becomes colorless if heated to 300° C.
Hardness 2-2.5
Cleavage Perfect 1 direction
Crystallography Isometric; crystals tiny; usually massive, granular.
Refractive Index 1.327
Birefringence None.
Luminescence None.
Luminescence Present No
Absorption Spectrum Not diagnostic.
Pleochroism Anomalous, strong: yellow/pink to deep carmine-red.
Optics N = 1.327. Isotropic. May show anomalous birefringence.
Luster Vitreous.
Specific Gravity 2.79
Enhancements Heating may make colored gems colorless.
Typical Treatments Heat Treatment
Transparency Transparent to translucent.

Optics: N: 1.327: isotropic.

Occurrence: In alkalic rocks, such as nepheline syenites.

Kola Peninsula, USSR.

Los, Guinea: Los is an island off the Guinea coast; facetable villiaumite occurs in nepheline syenite in reddish crystals, R.l. I l.33O—1.332, S.G. 2.79.

Francon Quarry, Mt. Ste. Hilaire, Quebec.

Comments: Villiaumite is seldom discussed among collectors of rare gemstones because until recently no facetable material was known. The material from Los was reported in 1976 and has been cut into tiny gemstones of deep red color. Despite their small size, they are desirable because so few stones exist. The material from Quebec is larger but very scarce. Villiaumite is somewhat water-soluble, and cutters must use special tricks (such as using alcohol as a cutting coolant) to facet the material.

Name: After M. Villiaume, a French explorer in whose collection of rocks from Guinea the material was first discovered.