Montebrasite
Brazil
2.56 carats
© Rarestone.com
Montebrasite is named after its discovery locality, at Montebras, Creuse, France.
Montebrasite forms attractive, colourless, bright yellow-green, sometimes blue, pink and pale brown, equant to short-prismatic crystals, twinning is common.
General Information |
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Chemical Formula | Walter Schumann, Gemstones of the world (2001) More from other references |
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Photos of natural/un-cut material from mindat.org |
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Physical Properties of Montebrasite |
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Mohs Hardness | 5.5 to 6Walter Schumann, Gemstones of the world (2001) More from other references |
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Specific Gravity | 2.98 to 3.10Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Tenacity | BrittleAnthony et al, Handbook of Mineralogy (2001) |
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Cleavage Quality | PerfectHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Fracture | Uneven,Sub-ConchoidalAnthony et al, Handbook of Mineralogy (2001) |
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Optical Properties of Montebrasite |
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Refractive Index | 1.578 to 1.646Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Optical Character | Biaxial/+Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Birefringence | 0.020 to 0.030Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Colour |
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Colour (General) | Colourless, yellowish, light green, light blue, white, pink.Walter Schumann, Gemstones of the world (2001) More from other references |
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Transparency | TransparentWalter Schumann, Gemstones of the world (2001) More from other references |
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Lustre | VitreousWalter Schumann, Gemstones of the world (2001) More from other references |
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Fluorescence & other light emissions |
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Fluorescence (Long-Wave UV) | Inert to weak greenHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Phosphorescence | May phosphoresce light blue to LW and SWHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Crystallography of Montebrasite |
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Crystal System | TriclinicHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Habit | Crystals typically equant, may be short to long prismatic, to 10 cm; as coarse cleavable or blocky to rounded nodular masses.Anthony et al, Handbook of Mineralogy (2001) |
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Geological Environment |
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Where found: | A late primary and secondary mineral in zoned granite pegmatites; may be an ore of lithium.Anthony et al, Handbook of Mineralogy (2001) |
Further Information |
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Mineral information: | Montebrasite information at mindat.org |
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Significant Gem Localities |
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| Brazil | |
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| | | Myanmar | |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
- Pein-Pyit (Painpyit; Pyan Pyit)
| Ted Themelis (2008) Gems & mines of Mogok |
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