Villiaumite Value, Price, and Jewelry Information

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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.