Jet
Lignite · C with impurities. Colors: black to dark brown.
- Mohs
- 2.5–4
- RI
- 1.66
- SG
- 1.19–1.35
- Crystal system
- organic
Jet at a glance.
- Species
- Lignite
- Formula
- C with impurities
- Crystal system
- organic
- Mohs
- 2.5–4
- RI
- 1.66
- SG
- 1.19–1.35
- Colors
- black to dark brown
What the encyclopedia says.
3 passages, quoted as published. Each links to the full entry and the sources of its chapter.
Minerals, rocks, organic gems and man-made stones
Several important gems do not. A rock is an aggregate of one or more minerals: lapis lazuli is a rock made mostly of blue lazurite with white calcite and brassy pyrite. A mineraloid is natural but lacks an ordered structure, and opal and obsidian are the usual examples. Organic gems come from living things. Pearl grows inside mollusks, precious coral is an animal skeleton, amber is fossilized tree resin and jet is a type of lignite formed from ancient wood.
Read the full entryCoral, amber, jet, ammolite, shell and ivory
Amber is fossilized tree resin. GIA gives it a refractive index of 1.540, a specific gravity of 1.08 and a hardness of 2–2.5, light enough to float in a saturated salt solution. Jet is a compact lignite formed from ancient wood, listed by CIBJO under the name jet or gagat.
Read the full entryMourning jewelry, talismans and amulets
The fashion peaked in Victorian Britain. After Prince Albert died in 1861, Queen Victoria stayed in mourning dress for the rest of her life, and black jewelry became expected of bereaved women who could afford it. Jet, a hard black fossilized wood found on the Yorkshire coast around Whitby, was the favored material. Whitby Museum counts over 200 jet factories employing 1,500 people at the height of the industry, between 1860 and 1880, supplied by 300 mines. Cheaper substitutes included black glass, sold as French jet, and vulcanite. Hairwork jewelry woven from a loved one's hair was also common. Elaborate mourning customs faded after World War I.
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