| General Information |
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| A variety or type of: | Tourmaline |
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| Chemical Formula | | Na(Mg | | )Al | | (Si | | O | | )(BO | | ) | | (OH) | | (OH) |
Gemdat.org, Management Team (2012) |
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| Dravite Treatments |
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| Color may be improved or created by irradiation of colorless to light colored stones (not detectable) - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 5 |
| Physical Properties of Dravite |
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| Mohs Hardness | 7Anthony et al, Handbook of mineralogy (2001) |
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| Specific Gravity | 3.03 to 3.18Anthony et al, Handbook of mineralogy (2001) |
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| Tenacity | BrittleAnthony et al, Handbook of mineralogy (2001) |
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| Cleavage Quality | PoorAnthony et al, Handbook of mineralogy (2001) |
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| Fracture | Uneven,Irregular,ConchoidalAnthony et al, Handbook of mineralogy (2001) |
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| Optical Properties of Dravite |
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| Refractive Index | 1.614 to 1.666Walter Schumann, Gemstones of the world (2001) |
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| Optical Character | Uniaxial/-Anthony et al, Handbook of mineralogy (2001) |
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| Birefringence | 0.014 to 0.032Walter Schumann, Gemstones of the world (2001) |
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| Pleochroism | Very strong: pale yellow - colorless,
yellowish, greenish, brownish.Anthony et al, Handbook of mineralogy (2001) |
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| Dispersion | 0.017Walter Schumann, Gemstones of the world (2001) |
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| Colour |
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| Colour (General) | Yellow brown to orangyHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Causes of Colour | Yellow to brown, related to titanium; due to Fe2+-O-Ti4+ charge transfer, with those low in iron yellow and those rich in iron brown. Red, Fe3+ pairs.W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) |
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| Transparency | Transparent,TranslucentAnthony et al, Handbook of mineralogy (2001) |
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| Lustre | Vitreous,ResinousAnthony et al, Handbook of mineralogy (2001) |
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| Fluorescence & other light emissions |
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| Fluorescence (Short Wave UV) | May weakly fluoresceAnthony et al, Handbook of mineralogy (2001) |
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| Crystallography of Dravite |
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| Crystal System | HexagonalAnthony et al, Handbook of mineralogy (2001) |
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| Habit | Crystals equant or short to long prismatic, with dominant pyramid faces, to 20 cm. Striated, cross sections typically triangular with curved convex sides. Commonly radiating, granular, and massive.Anthony et al, Handbook of mineralogy (2001) |
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| Geological Environment |
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| Where found: | Commonly in metamorphosed limestones or mafic igneous rocks with metasomatically introduced boron; rarely in pegmatites; as authigenic overgrowths in sedimentary rocks.Anthony et al, Handbook of mineralogy (2001) |
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| Further Information |
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| Mineral information: | Dravite information at mindat.org |
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| Significant Gem Localities |
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| Myanmar | | |
| Ted Themelis (2008) Gems & mines of Mogok |
- Dattaw-taung (Dattaw hill)
| Ted Themelis (2008) Gems & mines of Mogok |
- Pein-Pyit (Painpyit; Pyan Pyit)
| Ted Themelis (2008) Gems & mines of Mogok | | Sri Lanka | | |
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