sedimentary

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7.0 (Mohs scale); Color: Variegated browns, tans, greys, and yellows; Luster: Waxy to vitreous; Structure: Cryptocrystalline quartz preserving original wood cell structures; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Variegated browns, tans, greys, and yellows
Luster: Waxy to vitreous

Identified June 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through permineralization, where organic remains are replaced by minerals (usually silica) through groundwater over millions of years, often occurring in volcanic ash beds or sedimentary river deposits during the Mesozoic or Cenozoic eras.

Uses & applications

Used primarily in lapidary arts, jewelry, decorative furniture (tabletops), bookends, and as a popular collector's specimen.

Geological facts

In some specimens, the cellular structure of the original tree is so perfectly preserved that the specific genus and species can be identified by paleobotanists; the Petrified Forest National Park in Arizona is one of the world's most famous locations.

Field identification & locations

Identify by looking for distinct wood grain, bark textures, or growth rings in a heavy, cold-to-the-touch stony material that cannot be scratched by a steel knife. Common in the Western United States, Madagascar, and Indonesia.