Zektzerite
Zektzerite was discovered in 1968 on Kangaroo Ridge near Washington Pass in Okanogan County, Washington, USA. The chemical formula of Zektzerite is NaLiZrSi6O15 (Sodium Lithium Zirconium Silicate) and its molecular weight is 529.66 gm. This is the only known locality in the world for gem quality material. Zektzerite has a specific gravity of 2.79 (g/cm3) and the refractive index of 1.582 – 1.584 Biaxial ( – ). It is an exceedingly rare mineral and gem. Faceted gems are usually very small (less than 1/4 carat) and are colorless to pale pink. Zekzerite is possibly the rarest US gem.
Most mineral information sources list the discovery of Zektzerite as 1976. Actually, the initial discovery was made in 1968 on Kangaroo Ridge by Bart Cannon of Mercer Island, Washington. It wasn’t until 1976 that a sample of the mineral was sent to the Smithsonian Institution by Jack Zektzer of Seattle, Washington for analysis. A detailed investigation confirmed it as a new mineral species in 1976 and it was approved by the IMA in 1977. It was named after Jack Zekter in recognition of his efforts.
| Category: | Inosilicate |
| Chemical Formula: | NaLiZrSi6O15 |
| Sodium Lithium Zirconium Silicate | |
| Molecular Weight: | 529.66 gm |
| Composition: | Sodium | 4.34 % | Na | 5.85 % | Na2O |
| Lithium | 1.31 % | Li | 2.82 % | Li2O | |
| Zirconium | 17.22 % | Zr | 23.26 % | ZrO2 | |
| Silicon | 31.82 % | Si | 68.06 % | SiO2 | |
| Oxygen | 45.31 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Orthorhombic – Dipyramidal |
| Crystal Habit: | As stout pseudohexagonal prisms, showing {100}, {010}, and {011}, to 3.7 cm; flattened on {100} and lightly striated on {011}. |
| Twinning: | None |
| Cleavage: | Perfect on {100} and {010} |
| Fracture: | n/a |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.0 |
| Density: | 2.79 (g/cm3) |
| Luminescence: | Fluorescent; light yellow under SW UV |
| Radioactivity: | Not Radioactive |
| Color: | Colorless to Pink, Cream or White (commonly zoned) |
| Transparency: | Translucent |
| Luster: | Vitreous, Pearly on {100} |
| Refractive Index: | 1.582 – 1.584 Biaxial ( – ) |
| Birefringence: | 0.0020 (virtually isotropic) |
| Dispersion: | Very weak; r > v |
| Pleochroism: | None |
| Chemical Formula: | NaLiZrSi6O15 |
| Sodium Lithium Zirconium Silicate | |
| Molecular Weight: | 529.66 gm |
| Composition: | Sodium | 4.34 % | Na | 5.85 % | Na2O |
| Lithium | 1.31 % | Li | 2.82 % | Li2O | |
| Zirconium | 17.22 % | Zr | 23.26 % | ZrO2 | |
| Silicon | 31.82 % | Si | 68.06 % | SiO2 | |
| Oxygen | 45.31 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Orthorhombic – Dipyramidal |
| Crystal Habit: | As stout pseudohexagonal prisms, showing {100}, {010}, and {011}, to 3.7 cm; flattened on {100} and lightly striated on {011}. |
| Twinning: | None |
| Cleavage: | Perfect on {100} and {010} |
| Fracture: | n/a |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.0 |
| Density: | 2.79 (g/cm3) |
| Luminescence: | Fluorescent; light yellow under SW UV |
| Radioactivity: | Not Radioactive |
| Color: | Colorless to Pink, Cream or White (commonly zoned) |
| Transparency: | Translucent |
| Luster: | Vitreous, Pearly on {100} |
| Refractive Index: | 1.582 – 1.584 Biaxial ( – ) |
| Birefringence: | 0.0020 (virtually isotropic) |
| Dispersion: | Very weak; r > v |
| Pleochroism: | None |
