General Information |
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A variety or type of: | Tourmaline |
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Chemical Formula | Ca(Mg | | )MgAl | | (Si | | O | | )(BO | | ) | | (OH) | | (OH) | Gemdat.org, Management Team (2012) |
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Physical Properties of Fluor-uvite-Uvite Series |
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Mohs Hardness | 7.5Anthony et al, Handbook of mineralogy (2001) |
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Specific Gravity | 2.97 to 3.14Anthony et al, Handbook of mineralogy (2001) |
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Tenacity | BrittleAnthony et al, Handbook of mineralogy (2001) |
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Fracture | Uneven,ConchoidalAnthony et al, Handbook of mineralogy (2001) |
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Optical Properties of Fluor-uvite-Uvite Series |
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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 | Pale yellow - colorlessAnthony 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) | Brown, light to dark green, red, black; may be zoned parallel to prism faces.Anthony et al, Handbook of mineralogy (2001) |
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Causes of Colour | Green ("chrome tourmaline"), V3+ generally with minor amounts of Cr3+, both in octahedral coordinationW. 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 fluoresce a weak mustard-yellowAnthony et al, Handbook of mineralogy (2001) |
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Crystallography of Fluor-uvite-Uvite Series |
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Crystal System | HexagonalAnthony et al, Handbook of mineralogy (2001) |
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Habit | Crystals prismatic to equant, may be tabular, pyramidal, in radiating groups, to 15 cm. Cross sections are typically triangular with curved, convex sides.Anthony et al, Handbook of mineralogy (2001) |
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Geological Environment |
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Where found: | Typically in calcium-rich rocks subjected to contact metamorphism and metasomatic processes which added boron.Anthony et al, Handbook of mineralogy (2001) |
Further Information |
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Mineral information: | Fluor-uvite-Uvite Series information at mindat.org |
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Significant Gem Localities |
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