Jet
Jet is a compact, lightweight black organic gem material formed from fossilized wood. It takes a high polish, feels warm to the touch, and has been used for mourning jewelry and ornaments since antiquity.
Jet properties at a glance
| Type | Organic Gem Materials |
|---|---|
| Mohs hardness | 3 |
| Crystal system | amorphous |
| Luster | waxy |
| Streak | Brown |
| Cleavage | None |
| Fracture | Conchoidal |
| Specific gravity | 1.3 |
| Transparency | opaque |
| Common colors | Black, Dark brown |
| Rarity | uncommon |
Geology & background
Jet forms from waterlogged driftwood that was buried in fine sediment, compacted, and chemically altered into a hard, compact variety of lignite coal.
Jet was carved into beads and amulets in prehistoric times and became hugely popular for Victorian mourning jewelry after it was worn by Queen Victoria in her long period of mourning.
How to identify Jet
- Look for an opaque, deep black material that is very light in weight and warm to the touch.
- Jet leaves a brown streak and takes a high, slightly waxy polish without scratching easily.
- Distinguish it from black glass by its warmth and low density, and from coal by its toughness and even texture.
Where Jet is found
Jet occurs in carbonaceous shales and lignite-bearing strata, with notable sources in the United Kingdom, Spain, Germany, the United States, and Poland.
How much is Jet worth?
| Entry-level specimen | $5 |
|---|---|
| Typical collector specimen | $40 |
| Premium specimen | $300+ |
Value depends on color, polish, carving quality, size, condition, age, and provenance.
Common uses
- Mourning jewelry
- Beads and ornaments
- Carvings and inlay
- Buttons and decorative objects
- Collector specimens
Interesting facts
- The phrase jet black comes directly from the deep, even color of this gem material.
- Whitby in England became a famous source of jet, especially during the Victorian era.
- Jet can become electrically charged by rubbing, a property noted by writers in the ancient world.
- Because it is fossilized wood, jet is an organic gem material rather than a true mineral.
Care & safety
Jet is soft and somewhat brittle, so it scratches and chips more readily than most gem materials.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.
_1_(37046226390).jpg?width=320)
