sedimentary

Jet

Lignite coal variant (hydrocarbon polymer)

Hardness of 2.5 to 4 on the Mohs scale, deep black or dark brown color, vitreous to waxy luster, amorphous crystal structure, conchoidal fracture, specific gravity around 1.3 to 1.35

Identified August 3, 2026More sedimentary →

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Physical properties

Hardness of 2.5 to 4 on the Mohs scale, deep black or dark brown color, vitreous to waxy luster, amorphous crystal structure, conchoidal fracture, specific gravity around 1.3 to 1.35

Formation & geological history

Formed from the deep burial, compaction, and carbonization of wood from precursor trees (often Araucariaceae family) under high pressure over tens to hundreds of millions of years during the Jurassic and Cretaceous periods

Uses & applications

Used historically and currently for mourning jewelry, carved ornaments, rosaries, and by collectors

Geological facts

Jet has been used as a gemstone since the Neolithic period and gained immense popularity during the Victorian era when Queen Victoria wore it extensively as part of her mourning attire

Field identification & locations

Can be identified by its extremely light weight for its size, warm touch compared to cold stones, brownish-black streak, and the fact that it burns with a smoky flame and bituminous odor when heated