Vlasovite
Vlasovite is an extremely rare gem that was first discovered in 1961 at the Kola Peninsula, Russia and later found at the Kipawa alkaline complex next to Sheffield Lake, Temiscamingue County, Quebec, Canada. It is usually associated with Eudialyte. A very small amount of facet grade crystals were found at the Kipawa location in 1987. Gems are usually very small and slightly moderately included.
The main sources of gemmy crystals are Mt. Vavnbed, Lovozero massif, Kola Peninsula, Russia (Type Locality); fine crystals from the Sheffield Lake complex, Kipawa River, Villedieu Township, Quebec, Canada.
| Category: | Silicate mineral |
| Formula: | Na2ZrSi4O11 |
| Crystallography: | Monoclinic – Prismatic |
| Crystal Habit: | As crystals, to 15 cm; more commonly as subrounded to irregularly shaped grains and aggregates of such grains. |
| Twinning: | Twin plane [010], uncommon. |
| Cleavage: | [1011] Distinct/Good |
| Fracture: | Irregular/Uneven to Conchoidal |
| Tenacity: | Brittle |
| Hardness (Mohs): | 6.0 |
| Density: | 2.92 – 2.97 (g/cm3) |
| Luminescence: | Altered portions fluoresce brownish yellow under SW UV. |
| Radioactivity: | Not Radioactive |
| Other: | May invert to triclinic symmetry below 29 ±C. |
| Color: | Colorless, Pink, pale Yellow, pale Brown, Silvery |
| Transparency: | Transparent |
| Luster: | Greasy; highly Vitreous to Pearly on cleavage surfaces |
| Refractive Index: | 1.605 – 1.628 Biaxial ( – ) |
| Birefringence: | 0.0210 |
| Dispersion: | Distinct; r > v |
| Pleochroism: | Colorless |
