Gilalite
Gilalite is an uncommon copper that is hydrated that was discovered in 1979 as green to blue-green spherules of radial materials to 0.3mm in diameter at the Christmas time Mine in Gila County, Arizona, USA. Minute, clear crystals have been discovered, but too small for faceting. Gilalite is never ever a gem that is faceted its own but is definitely an unusual and very attractive inclusion in Quartz. As a gem material Gilalite ended up being discovered at São José da Batalha, Salgadinho, Borborema mineral province, Paraíba, Ceará, Brazil in, 2004 as beautiful inclusions in Quartz August. It occurs as small spherules or circular fibres of light to dark green, blue and blue-green. Quartz with Gilalite inclusions normally referred to as “Paraiba Quartz” due to the color similarities to Paraiba selection of Tourmaline; or “Medusa Quartz” because, under magnification, the small balls of Gilalite suspended in Quartz resemble the shape of a jellyfish that is floating Medusas Rondeau. GIA had articles in the Fall 2005 (Volume 41, Issue 3) of Gems & Gemology about Medusa Quartz.
Areas for finding Gilalite: São José da Batalha, Salgadinho, Borborema mineral province, Paraíba, Ceará, Brazil; Lavrion District slag localities, Lavrion District, Attiki Prefecture, Greece. Into the USA: Christmas Mine, Banner District, Dripping Spring Mountains, Gila County, Arizona and the Lonestar deposit, near Safford, Graham County, Arizona; employer Mine, Goodsprings District, Nevada.
| Category: | Silicate mineral |
| Chemical Formula: | Cu5Si6O17 · 7(H2O) (in Quartz – SiO2) |
| Hydrated Copper Silicate (in Quartz) | |
| Molecular Weight: | 884.34 gm |
| Composition: | Copper | 35.93 % | Cu | 44.97 % | CuO |
| Silicon | 19.06 % | Si | 40.77 % | SiO2 | |
| Hydrogen | 1.60 % | H | 14.26 % | H2O | |
| Oxygen | 43.42 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Monoclinic (probable) |
| Crystal Habit: | As spherules of radial fibers, to 0.3 mm. |
| Twinning: | None |
| Cleavage: | n/a |
| Fracture: | n/a |
| Tenacity: | Waxy or gummy |
| Moh’s Hardness: | 2.0 |
| Density: | 2.72 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Chrysocolla-green, inclining to pale blue-green. |
| Transparency: | Transparent to Translucent |
| Luster: | Nonmetallic |
| Refractive Index: | 1.560 – 1.635 Biaxial ( – ) |
| Birefringence: | 0.075 |
| Dispersion: | None |
| Pleochroism: | Weak in drab grayish green |
