Painite
Painite is a very rare borate mineral. It was first found in Myanmar by British mineralogist and gem dealer Arthur C.D. Pain who misidentified it as ruby, until it was discovered as a new gemstone in the 1950s. When it was confirmed as a new mineral species, the mineral was named after him.[2]
| Painite | |
|---|---|
 Painite from Myanmar, 2 cm long | |
| General | |
| Category | Borate minerals |
| Formula (repeating unit) | CaZrAl9O15(BO3) |
| Strunz classification | 6.AB.85 |
| Dana classification | 7.5.2.1 |
| Crystal system | Hexagonal[1] |
| Crystal class | Dipyramidal (6/m) (same H-M symbol), although earlier reported as hexagonal (6)[2] |
| Space group | P63/m |
| Unit cell | a = 8.72 Å, c = 8.46 Å; Z = 2 |
| Identification | |
| Color | Red, brownish, orange-red |
| Crystal habit | Elongated crystals, pseudo-orthorhombic[3][2] |
| Mohs scale hardness | 8 |
| Luster | Vitreous |
| Streak | red |
| Diaphaneity | Transparent |
| Specific gravity | 4.01 |
| Optical properties | Uniaxial (-) |
| Refractive index | no = 1.8159, ne = 1.7875[3] |
| Pleochroism | Ruby-red parallel to [0001]; pale brownish orange or pale red-orange at right angles to [0001] |
| Melting point | 2094 |
| Solubility | Insoluble in acids[3] |
| References | [2][4][5] |
The chemical makeup of painite contains calcium, zirconium, boron, aluminium and oxygen (CaZrAl9O15(BO3)). The mineral also contains trace amounts of chromium and vanadium, which are responsible for Painite's typically orange-red to brownish-red color,[1][6] similar to topaz. The crystals are naturally hexagonal in shape, and, until late 2004, only two had been cut into faceted gemstones.[7]
Discovery and occurrence
Extensive exploration in the Mogok region has identified several new painite occurrences that have been vigorously explored resulting in several thousand new available painite specimens.[6]
Striated, euhedral painite crystal (size: 0.9×0.8×0.7 cm)
References
- T Armbruster; N Dobelin; A Peretti; D Gunther; E Reusser; B Grobety (2004). "The crystal structure of painite CaZrB(Al9O18) revisited" (PDF). American Mineralogist. 89: 610–613. Archived from the original (PDF) on 2016-03-04. Retrieved 2012-05-28.
- Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (2003). "Paynite". Handbook of Mineralogy (PDF). V (Borates, Carbonates, Sulfates). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209740. Retrieved December 5, 2011.
- Claringbull GF, Hey MH, Payne CJ (1957). "Painite, a New Mineral from Mogok, Burma". Mineralogical Magazine. 31 (236): 420–5. doi:10.1180/minmag.1957.031.236.11.
- Painite. Webmineral. Retrieved on 2012-05-28.
- Painite. Mindat.org. Retrieved on 2012-05-28.
- Painite history at Caltech. Minerals.gps.caltech.edu. Retrieved on 2012-05-28.
- Ten gemstones that are rarer than diamond. io9.com
External links
