Alabaster
Alabaster is named after its supposed early source at Alabaston, a town in Egypt.
Alabaster is the massive variety of Gypsum, which can occur as transparent crystals often twinned in swallow-tailed forms. The purest form of alabaster is white and translucent but the impurities (e.g. ferric oxide) can colour the stone in yellows, browns and black in veins or patches.
Alabaster has been used as an ornamental stone for a long time.
Alabaster is the massive variety of Gypsum, which can occur as transparent crystals often twinned in swallow-tailed forms. The purest form of alabaster is white and translucent but the impurities (e.g. ferric oxide) can colour the stone in yellows, browns and black in veins or patches.
Alabaster has been used as an ornamental stone for a long time.
| General Information | |||||||||||||||||
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| A variety or type of: | Gypsum | ||||||||||||||||
| Chemical Formula |
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| Alabaster Treatments | |||||||||||||||||
| Webster (p.298) reports that carved alabaster objects are often immersed in cold water, the temperature of which is slowly raised to boiling and then again slowly cooled; these changes are the appearance of the alabaster so that it looks more like the much harder white marble. Heating may 'open pores' or produce cracks which permit better penetration of dyes. Dyeing and colored oiling have often been used to make alabaster more attractive and, for example, to distinguish the two colors in chess boards and in carved chess pieces. Carbed objects are also often waxed and may be coated with paint when in statue form - Nassau (1984) | |||||||||||||||||
| Physical Properties of Alabaster | |||||||||||||||||
| Mohs Hardness | 2, Gemstones of the world (2001) More from other references | ||||||||||||||||
| Specific Gravity | 2.30 to 2.33, Gems, Sixth edition (2006) | ||||||||||||||||
| Cleavage Quality | Good, Gems, Sixth edition (2006) | ||||||||||||||||
| Optical Properties of Alabaster | |||||||||||||||||
| Refractive Index | 1.520 to 1.530, Gemstones of the world (2001) More from other references | ||||||||||||||||
| Birefringence | +0.010, Gemstones of the world (2001) | ||||||||||||||||
| Dispersion | None, Gemstones of the world (2001) | ||||||||||||||||
| Colour | |||||||||||||||||
| Colour (General) | White, pink, brownish., Gemstones of the world (2001) More from other references | ||||||||||||||||
| Transparency | Translucent,Opaque, Gemstones of the world (2001) Translucent at edgesMore from other references | ||||||||||||||||
| Fluorescence & other light emissions | |||||||||||||||||
| Fluorescence (General) | Usually a brownish shade, Gems, Sixth edition (2006) | ||||||||||||||||
| Crystallography of Alabaster | |||||||||||||||||
| Crystal System | Monoclinic, Gems, Sixth edition (2006) | ||||||||||||||||
| Habit | Massive, Gems, Sixth edition (2006) | ||||||||||||||||
| Geological Environment | |||||||||||||||||
| Where found: | It may be formed in mineral veins where sulphuric acid, derived from the oxidation of pyrite and other sulphides, has acted upon limestone., Gems, Sixth edition (2006) | ||||||||||||||||
| Further Information | |||||||||||||||||
| Mineral information: | Alabaster information at mindat.org | ||||||||||||||||
| Significant Gem Localities | |||||||||||||||||
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