Painite from Myanmar, 2 cm long
|Crystal class||Dipyramidal (6/m) |
(same H-M symbol), although earlier reported as hexagonal (6)
|Unit cell||a = 8.72 Å, |
c = 8.46 Å; Z = 2
|Color||Red, brownish, orange-red|
|Crystal habit||Elongated crystals, pseudo-orthorhombic|
|Mohs scale hardness||8|
|Optical properties||Uniaxial (-)|
|Refractive index||no = 1.8159, ne = 1.7875|
|Pleochroism||Ruby-red parallel to ; pale brownish orange or pale red-orange at right angles to |
|Solubility||Insoluble in acids|
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.
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, similar to topaz. The crystals are naturally hexagonal in shape, and, until late 2004, only two had been cut into faceted gemstones.
Discovery and occurrence
- 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.
- 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
- Media related to Painite at Wikimedia Commons
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