Jet
Jet is an organic mineral recognized among collectors for its crystal form and distribution.
Jet is a hard, velvety-black organic gem material — a form of fossilised wood, essentially a compact lignite coal — long carved into mourning jewellery.
About Jetextended article
Jet is not a true mineral but a mineraloid: a black, lightweight organic material formed from wood that was buried, compressed and fossilised into a hard, compact form of lignite coal. It takes a high polish and has been used for ornaments since prehistoric times.
Identifying jet
Jet is deep velvety black, lightweight, and warm to the touch compared with cold mineral 'black' stones. It is fairly soft (2.5–4), takes a bright polish, and can hold a static charge when rubbed. It is opaque with a waxy to glassy lustre on polished surfaces.
Where it is found
The most famous jet comes from Whitby, on the coast of Yorkshire in England, where it weathers from Jurassic shales. Whitby jet became hugely fashionable for Victorian mourning jewellery and remains the benchmark for the material.
About Jet
Jet is classified as an organic mineral in the organic gemstones (not a mineral group) and has the chemical formula Lignitic coal (fossilized wood) — not a mineral. It crystallizes in the amorphous system and is relatively soft, requiring careful handling.
Identification & care
Jet typically forms massive, often retaining wood grain structure. Its color is typically intense black. The luster is waxy to resinous, velvety on polished surface, the streak is brownish black, and specimens are typically opaque. The fracture is conchoidal, which is one of its key identifying features.
Collector context
Collector notes
For decorative mineral collectors, Jet is appreciated for its visual character.
References & databases
Mindat.org is the world’s largest open mineralogy database. Our descriptions are written independently and fact-checked.