| General Information |
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| A variety or type of: | Quartz |
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| Chemical Formula | Michael O’Donoghue, Gems, Sixth Edition (2006) |
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| Photos of natural/un-cut material from mindat.org |
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| Physical Properties of Prase |
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| Mohs Hardness | 7Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Specific Gravity | 2.64 to 2.69Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Cleavage Quality | NoneArthur Thomas, Gemstones (2009) |
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| Fracture | ConchoidalMichael O’Donoghue, Gems, Sixth Edition (2006) |
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| Optical Properties of Prase |
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| Refractive Index | 1.544 to 1.553Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Optical Character | Uniaxial/+Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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| Birefringence | 0.009Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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| Colour |
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| Colour (General) | Grayish green color due actinolite fibers, blue color due to crocidolite fibersHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Causes of Colour | Chlorite inclusionsWalter Schumann, Gemstones of the world (2001) |
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| Transparency | Transparent,Translucent,OpaqueUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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| Lustre | VitreousArthur Thomas, Gemstones (2009) |
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| Crystallography of Prase |
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| Crystal System | TrigonalUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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| Habit | PrismaticMichael O’Donoghue, Gems, Sixth Edition (2006) |
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| Further Information |
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| Mineral information: | Prase information at mindat.org |
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