| General Information | ||||||||||||||||||||||
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| Chemical Formula |
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| Physical Properties of Dumortierite | ||||||||||||||||||||||
| Mohs Hardness | 7, Gemmological Tables (2004) More from other references | |||||||||||||||||||||
| Specific Gravity | 3.31, Gemmological Tables (2004) More from other references | |||||||||||||||||||||
| Cleavage Quality | None, Gemstones (2009) | |||||||||||||||||||||
| Fracture | Uneven, Gemstones (2009) | |||||||||||||||||||||
| Optical Properties of Dumortierite | ||||||||||||||||||||||
| Refractive Index | 1.669 to 1.723, Blue Chart Gem Identification (2010) Rare red-brown crystals +/- 1.669More from other references | |||||||||||||||||||||
| Optical Character | Biaxial/-, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Birefringence | 0.011 to 0.037, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Pleochroism | Strong trichroism for rare red-brown crystals: black - red brown - brown, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Dispersion | Nil, Gemstones (2009) | |||||||||||||||||||||
| Colour | ||||||||||||||||||||||
| Colour (General) | Blue, green, blue-green, brown, red-brown, reddish, violet, Gemmological Tables (2004) More from other references | |||||||||||||||||||||
| Transparency | Transparent,Translucent,Opaque, Gemmological Tables (2004) More from other references | |||||||||||||||||||||
| Lustre | Vitreous, Gemstones (2009) Dull | |||||||||||||||||||||
| Fluorescence & other light emissions | ||||||||||||||||||||||
| Fluorescence (Short Wave UV) | Inert to chalky blue, often intergrown with quartz, Blue Chart Gem Identification (2010) | |||||||||||||||||||||
| Crystallography of Dumortierite | ||||||||||||||||||||||
| Crystal System | Orthorhombic, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Habit | Commonly fibrous aggregate, Gemmological Tables (2004) More from other references | |||||||||||||||||||||
| Geological Environment | ||||||||||||||||||||||
| Where found: | Dumortierite occurs in pegmatite veins or in aluminium-rich regionally metamorphosed rocks., Gems, Sixth Edition (2006) | |||||||||||||||||||||
| Further Information | ||||||||||||||||||||||
| Mineral information: | Dumortierite information at mindat.org | |||||||||||||||||||||