Aventurine
The name aventurine derives from the Italian "a ventura" meaning "by chance". Aventurine is a feebly translucent, fine-grained to compact variety of
Quartz, the surface of which has a speckled, metallic sheen, usually of a reddish-brown colour, but occasionally yellow, white, blue or green. This appearance is caused by the presence, in the colourless
quartz substance, of numbers of enclosures (scales of mica, plates of chrome-mica fuchsite, etc.), which can always be seen with the aid of the microscope, and sometimes with a simple lens, or with the naked eye.
| General Information |
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| A variety or type of: | Quartz |
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| Chemical Formula | Walter Schumann, Gemstones of the world (2001) |
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| Synthetic Aventurine |
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| Aventurine-glass is an artificial product which resembles natural aventurine but possesses an even finer appearance. It is a colourless glass in which are embedded numerous small red octahedra, the faces of which are equilateral triangles. The chemical composition of the material, the well-defined crystalline form, together with the red colour and strong metallic lustre of the enclosures, point to the fact that the latter consists of metallic copper. The much lower hardness of aventurine-glass, together with the form of the enclosures, which can be readily made out with a lens, definitely distinguishes it in all cases from natural aventurine and from sunstone. - Precious stones, Max Bauer, 1968, p 503 |
| Physical Properties of Aventurine |
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| Mohs Hardness | 6Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Specific Gravity | 2.62 to 2.67Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Tenacity | BrittleWalter Schumann, Gemstones of the world (2001) |
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| Cleavage Quality | NoneWalter Schumann, Gemstones of the world (2001) |
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| Fracture | Conchoidal,SplinteryMax Bauer, Precious stones (1968) |
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| Optical Properties of Aventurine |
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| Refractive Index | 1.525 to 1.552Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Optical Character | Biaxial/-Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Birefringence | 0.007 to 0.010Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Pleochroism | AbsentWalter Schumann, Gemstones of the world (2001) |
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| Dispersion | NoneWalter Schumann, Gemstones of the world (2001) |
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| Colour |
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| Colour (General) | Green, red-brown, gold-brownWalter Schumann, Gemstones of the world (2001) More from other references |
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| Colour (Chelsea Filter) | ReddishHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Causes of Colour | Green, chromian mica (fuchsite) inclusions. Greenish yellow, color center.W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) |
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| Transparency | Translucent,OpaqueWalter Schumann, Gemstones of the world (2001) More from other references |
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| Fluorescence & other light emissions |
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| Fluorescence (General) | Green aventurine: reddishWalter Schumann, Gemstones of the world (2001) More from other references |
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| Crystallography of Aventurine |
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| Crystal System | TriclinicHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Habit | MassiveWalter Schumann, Gemstones of the world (2001) |
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| Geological Environment |
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| Where found: | Occurs both in primary deposits and also as loose pebbles.Max Bauer, Precious stones (1968) |
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| Inclusions in Aventurine |
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| Aventurescence caused by platy inclusions of green mica (fuchsite) - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7 |
| Further Information |
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| Mineral information: | Aventurine information at mindat.org |
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| Significant Gem Localities |
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| Austria | |
- Bruck-Mürzzuschlag District
| Max Bauer, Precious stones (1968) | | India | | |
| Max Bauer, Precious stones (1968) |
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