Jet
Jet is an opaque black coalified fossilized drift wood of trees of the family Araucariaceae which is 180 million years old.
Jet is chemically related to brown coal, or lignite, but Jet is more solid and tough.
Jet has been used both as a talisman and a jewel for over four thousand years.
Jet is found in several locations around the world, but only the British and Spanish deposits have been worked commercially.
Jet is chemically related to brown coal, or lignite, but Jet is more solid and tough.
Jet has been used both as a talisman and a jewel for over four thousand years.
Jet is found in several locations around the world, but only the British and Spanish deposits have been worked commercially.
| Physical Properties of Jet | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mohs Hardness | 2.5 to 4, Blue Chart Gem Identification (2010) More from other references | |||||||||||
| Specific Gravity | 1.19 to 1.35, Gemstones of the world (2001) More from other references | |||||||||||
| Cleavage Quality | None, Gemstones of the world (2001) | |||||||||||
| Fracture | Conchoidal, Gemstones of the world (2001) More from other references | |||||||||||
| Optical Properties of Jet | ||||||||||||
| Refractive Index | 1.640 to 1.680, Blue Chart Gem Identification (2010) More from other references | |||||||||||
| Optical Character | Isotropic, Gemmological Tables (2004) | |||||||||||
| Birefringence | None, Gemstones of the world (2001) | |||||||||||
| Pleochroism | Absent, Gemstones of the world (2001) | |||||||||||
| Dispersion | None, Gemstones of the world (2001) | |||||||||||
| Colour | ||||||||||||
| Colour (General) | Deep black, dark brown, Gemstones of the world (2001) More from other references | |||||||||||
| Transparency | Opaque, Gemmological Tables (2004) More from other references | |||||||||||
| Lustre | Waxy,Dull, Management Team (2012) Dull to waxy, but takes an extremely high polish to an almost mirror-finish.More from other references | |||||||||||
| Fluorescence & other light emissions | ||||||||||||
| Fluorescence (General) | None, Gemstones of the world (2001) | |||||||||||
| Crystallography of Jet | ||||||||||||
| Crystal System | Amorphous, Blue Chart Gem Identification (2010) | |||||||||||
| Inclusions in Jet | ||||||||||||
| Hot needle: petroleum, coal odor (fossilized wood) - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 4 | ||||||||||||
| Further Information | ||||||||||||
| Mineral information: | Jet information at mindat.org | |||||||||||
| Significant Gem Localities | ||||||||||||
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