Villiaumite: Gemstones Information
Villiaumite is NaF and most commonly forms translucent to transparent carmine-red to lavender-pink granular masses of the cubic system; the cubic crystals are rare and show a perfect cleavage in one direction with hardness 2–2.5 and SG 2.79. The RI is 1.327–1.328. Villiaumite may show anomalous anisotropism and yellow to pink/deep carmine pleochroism.Villiaumite occurs in nepheline syenite and nepheline syenite pegmatites. Very small faceted stones have been obtained from crystals found at Rouma Isle, Los Islands, Guinea. Some gem-quality material or at least larger crystals has been found at Mt Saint Hilaire, Quebec,Canada. Villiaumite is likely to be water-soluble and may show weak red fluorescence under SWUV.