| General Information |
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| Chemical Formula | Michael O’Donoghue, Gems, Sixth Edition (2006) More from other references |
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| Sugilite Treatments |
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| It has been noted by J.Call (unpublished observation) that dark purple sugilite can be lightened by heating at about 450°C; the product may have a banded appearance - Nassau (1984) |
| Sugilite Simulants |
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| May be mixed with chalcedony - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 5 |
| Physical Properties of Sugilite |
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| Mohs Hardness | 5.5 to 6.5Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Specific Gravity | 2.74 to 2.80Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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| Cleavage Quality | PoorArthur Thomas, Gemstones (2009) |
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| Fracture | Sub-ConchoidalArthur Thomas, Gemstones (2009) |
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| Refractive Index | 1.607 to 1.612Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Optical Character | Uniaxial/-Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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| Birefringence | |
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