Painite
Painite is a rare borate mineral. Until recently, Painite was thought to be the rarest of all gemstones with only a couple faceted gems in existence. The chemical formula of Painite is CaZrAl9O15(BO3) (Calcium Zirconium Aluminum Borate) and its molecular weight is 586.42 gm. At first, the only mineral specimen was a red crystal kept in the British Museum in London, weighing 1.7 grams which were discovered in 1951 and identified in 1957 as a new mineral. The Moh’s Hardness is ~8.0 and the specific gravity 4.01 – 4.03 (g/cm3). Eventually, other crystals were identified and finally, a faceted gem came into existence. The recent find in Mogok has brought Painite to the market in greater quantities but it is still a rare gem. The only two sources of Painite are from near Ohngaing Village (which is also the type locality) and Kyauk-Pyat-Thet, both in Mogok, Sagaing District, Mandalay Division, Myanmar (Burma). Painite is a member of the Fluoborite – Painite mineral series that also includes Jeremejevite.
| Category: | Borate minerals |
| Chemical Formula: | CaZrAl9O15(BO3) |
| Calcium Zirconium Aluminum Borate | |
| Molecular Weight: | 586.42 gm |
| Composition: | Sodium | 0.74 % | Na | 1.00 % | Na2O |
| Calcium | 5.26 % | Ca | 7.36 % | CaO | |
| Zirconium | 0.62 % | Zr | 0.84 % | ZrO2 | |
| Titanium | 1.55 % | Ti | 2.59 % | TiO2 | |
| Aluminum | 40.49 % | Al | 76.50 % | Al2O3 | |
| Chromium | 0.27 % | Cr | 0.35 % | CrO | |
| Boron | 1.95 % | B | 6.29 % | B2O3 | |
| Oxygen | 49.11 % | O | |||
| 100.00 % | 94.94 % | = TOTAL OXIDE |
| Crystallography: | Hexagonal – Dipyramidal |
| Crystal Habit: | Crystals are elongated, pseudo-orthorhombic, to 1.5 cm |
| Twinning: | Common |
| Cleavage: | None |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | ~8.0 |
| Density: | 4.01 – 4.03 (g/cm3) |
| Luminescence: | Not Fluorescent; weak red under LW UV, strong red under SW UV |
| Radioactivity: | Not Radioactive |
| Color: | Deep garnet-red, brownish red-orange. |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous (glassy) |
| Refractive Index: | 1.787 – 1.816 Uniaxial ( – ) |
| Birefringence: | 0.0270 – 0.0280 |
| Dispersion: | n/a |
| Pleochroism: | e = ruby-red; w = pale brownish orange or pale red-orange |
