Amethyst
Amethyst Super Trillion Cut
105.01 carats
© johndyergems.com
Amethyst is the name given to purple to mauve
quartz.
The name comes from the Ancient Greek ("not intoxicated"), a reference to the belief that the stone protected its owner from drunkenness. The ancient Greeks and Romans wore amethyst and made drinking vessels of it in the belief that it would prevent intoxication.
The range of colour includes reddish-violet tints of pale or almost colourless shades, and deep, rich tones of pure violet.
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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Amethyst Treatments |
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Heat treatment between 878 - 1382 degrees F (470 - 750 degrees C) produces light yellow, red-brown, green, or colorless varieties. The original color an be restored by X-ray radiation. - Gemstones of the world, Walter Schumann, 2001, p 118 |
Synthetic Amethyst |
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Synthetic amethyst produced by hydrothermal method entered the market in 1970s. |
Physical Properties of Amethyst |
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Mohs Hardness | 7Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Specific Gravity | 2.65Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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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 | ConchoidalWalter Schumann, Gemstones of the world (2001) |
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Heat Sensitivity | The colour does not resist high temperatures. When subjected to the action of heat it changes first to a more or less pronounced yellow, gradually assumes a greenish shade, and finally disappears.Max Bauer, Precious Stones (1968) Dover Publications |
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Optical Properties of Amethyst |
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Refractive Index | 1.544 to 1.553Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Birefringence | 0.009Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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Pleochroism | Weak: (gray)-purple - reddish-purpleHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Dispersion | 0.013Walter Schumann, Gemstones of the world (2001) |
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Colour |
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Colour (General) | Purple, violet, pale red-violetWalter Schumann, Gemstones of the world (2001) More from other references |
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Colour (Daylight) | Some amethysts lose some color in daylight.Walter Schumann, Gemstones of the world (2001) |
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Colour (Chelsea Filter) | ReddishHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Causes of Colour | Violet to purple, O2+→Fe4+ charge transfer, due to irradiation.W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) |
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Transparency | Transparent,TranslucentUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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Fluorescence & other light emissions |
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Fluorescence (General) | Inert to weak greenish or bluishHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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Crystallography of Amethyst |
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Crystal System | TrigonalUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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Habit | Hexagonal prismsWalter Schumann, Gemstones of the world (2001) |
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Geological Environment |
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Where found: | Found in geodes in alluvial deposits.Walter Schumann, Gemstones of the world (2001) |
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Inclusions in Amethyst |
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Typical "zebra stripe" pattern, 2 phase inclusions in veil-like pattern - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7
Healing cracks ("tiger-stripes"), Brazilian law twinning - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 9 |
Further Information |
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Mineral information: | Amethyst information at mindat.org |
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Significant Gem Localities |
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| Bolivia | |
| Laurs (2001, 2010) |
| Laurs (2001, 2010) |
| Laurs (2001, 2010) | | Brazil | |
| Couto (2000) |
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| Priester (1999) |
| Rocks & Min.:5:131. |
| Rocks & Min.: 5:131. |
| Rocks & Min.:5:131. |
| Balzer (1999) |
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| R. Batista and D. Epstein (2000) | | Cambodia | |
| Ngu and Ngoc (1986) | | Canada | |
| Garland (2004) |
| Sinkankas (1997) |
| Sinkankas (1997) | | India | |
| S. Fernandes (1999) | | Kenya | |
| Henn and Milisenda (2001) | | Madagascar | |
| Aurisicchio et al. (1999) |
| Madagascar, extraLapis English No.1, 2001, p. 44 |
| Pezzotta (1999) |
| Madagascar - extraLapis English No.1, p. 92 | | Mexico | |
- Eduardo Neri Municipality
| Ontiveros et al. (2004) |
| Ontiveros et al. (2004) | | Myanmar | |
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| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok |
| Ted Themelis (2008) Gems & mines of Mogok | | Namibia | |
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| Michelou (2006) | | Nigeria | |
| Laurs and Koivula (2003) | | Peru | |
| | | Russia | |
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| P. Lyckberg (2009) |
| V. Bukanov (1999) |
| V. Bukanov (1999) | | South Korea | |
- South Gyeongsang Province
| Yang et al. (2001) | | Sri Lanka | |
| | | Uruguay | |
| Gilg et al. (2003) |
| mindat.org | | USA | |
| Lowell and Koivula (2004) |
| Laurs (2005) |
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