fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness of 6.5 to 7 on the Mohs scale, variable colors including brown, grey, red, and yellow, vitreous to waxy luster, amorphous crystal structure (microcrystalline quartz/chalcedony), conchoidal fracture, specific gravity around 2.5 to 2.7.

Identified August 3, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization when buried organic wood material is saturated with silica-rich groundwater over millions of years, typically ranging from 50 to over 200 million years old.

Uses & applications

Used in ornamental carvings, high-end jewelry, decorative furniture, tabletops, and as prized collector specimens.

Geological facts

Petrified wood retains the original cellular structure of the tree while completely replacing the organic matter with stone. Entire forests of petrified trees can be found, such as in the Petrified Forest National Park in Arizona.

Field identification & locations

Easily identified by its distinct wood-like grain and bark texture combined with a stony weight and ringing sound when struck. Common worldwide in sedimentary rock layers associated with ancient floodplains and volcanic ash deposits.