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Villiaumite
Current inventory:  2 gems
 

Chemistry:  NaF

Discovered in 1908;   IMA status: Valid (pre-IMA; Grandfathered).
Villiaumite is named in honor of Maxime Villiaume, French explorer, in whose collections of rocks from Guinea the mineral Villiaumite was first found.

Classification

Mineral Classification:

Halides

Strunz 8th Ed. ID:

3/A.02-10

Nickel-Strunz 10th Ed. ID:

3.AA.20

3 : HALIDES
A : Simple halides, without H₂O
A : M:X = 1:1, 2:3, 3:5, etc.

Related to:

Halite Group: Griceite, Villiaumite, Carobbiite, Halite, Sylvite, Chlorargyrite, Bromargyrite. Griceite-Bromargyrite Series

Crystal Data

Crystallography:

Isometric - Hexoctahedral

Crystal Habit:

Crystals are rare, cubic, to 15 cm; commonly granular, massive.

Twinning:

None

Physical Properties

Cleavage:

[100] Perfect, [010] Perfect, [001] Perfect

Fracture:

Irregular to Uneven

Tenacity:

Brittle

Hardness (Mohs):

2.0 - 2.5

Hardness (Vickers):

VHN200=1239 - 1467 kg/mm²

Density:

2.79 - 2.80 (g/cm³)

Luminescence:

Fluorescent; glows Yellow under SW UV and LW UV

Radioactivity:

Not Radioactive

Other:

Soluble in water

Health Warning:

CAUTION: Poisonous! Do not lick or ingest. Wash hands after handling!

Optical Properties

Color:

Carmine Red, Dark Red, Pink, Lavender-Pink, Light Orange, Orangish Brown

Transparency:

Transparent to Translucent

Luster:

Vitreous (glassy)

Refractive Index:

1.327 - 1.328  Isotropic; weak anomalous birefringence, then Uniaxial ( - )

Birefringence:

0.00  Isotropic (weak anomalous birefringence)

Dispersion:

n/a

Pleochroism:

Strong; E = Yellow, O = Pink to deep Red

Occurances

Geological Setting:

In nepheline syenite and nepheline syenite pegmatites; in lake-bed deposits.

Common Associations:

Aegirine, Chkalovite, Eudialyte, Lamprophyllite, Nepheline, Neptunite, Pectolite, Serandite, Sodalite, Ussingite, Zeolites

Type Locality:

Rouma Island (Roume; Roma; Ruma), Los Archipelago (Los Islands), Guinea

Year Discovered:

1908

View mineral photos:

Villiaumite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Villiaumite is a strongly colored Halide. Its deep, carmine red color is almost unique in the gem world. Other colorful Halide gems include Fluorite and Boleite. Villiaumite is an extremely rare gem since facetable crystals are rarely found and the mineral is very soft (2.0 - 2.5), has perfect cleavage and is slightly soluble in water. Since it is a sodium salt, and is water soluble, Villiaumite should be kept very dry, maybe even stored with a desicant, to avoid moisture absorption which could destroy mineral specimens or gemstones.

Villiaumite is found in only a few locations worldwide, including Rouma Isle, Los Islands, Guinea (the Type Locality); Mts. Karnasurt and Alluaiv, Lovozero massif, and from the Khibiny massif, Kola Peninsula, Russia; Kvanefjeld, Il´imaussaq intrusion, Greenland; Aris, about 20 km south of Windhoek, Namibia; Lake Magadi, Kenya; Po¸cos de Caldas, Minas Gerais, Brazil; in the USA, at Point of Rocks, Colfax County, New Mexico; on Porphyry Mountain, Jamestown district, Boulder County, Colorado; relatively large crystals from Mont Saint-Hilaire, Quebec, Canada.

Most of these sources only produce massive material not suitable for faceting. Mont Saint-Hilaire, Quebec, Canada and Khibiny massif, Kola Peninsula, Russia were about the only sources of facetable crystals and these crystals are very rare even from these locations. The most signigicant new find of gem quality Villiaumite crystals is from the Aris Quarries (Ariskop Quarry; Railway Quarry), Aris, Windhoek, Windhoek District, Khomas Region, Namibia.
 

  
Villiaumite gems for sale: