fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Shades of brown, tan, cream, beige, and reddish tones with distinct wood grain banding; Luster: Vitreous to waxy when polished; Crystal Structure: Microcrystalline (trigonal quartz pseudomorph); Cleavage: None, exhibits conchoidal fracture.

Hardness: 6
Luster: Vitreous to waxy when polished

Identified July 24, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization, a process where organic wood materials are gradually replaced with silica-rich minerals (like chalcedony and microcrystalline quartz) deposited by groundwater over millions of years, maintaining the original cellular structure of the plant.

Uses & applications

Used widely for lapidary arts, decorative displays, polished specimens, cabochons for jewelry, paperweights, and educational collections.

Geological facts

Petrified wood can retain cellular-level detail, allowing paleobotanists to identify tree species that lived tens to hundreds of millions of years ago. The Arizona Petrified Forest is one of the most famous locations worldwide for colorful fossilized trees.

Field identification & locations

Identify in the field by looking for distinct tree ring, bark, or wood grain patterns combined with high hardness and quartz-like density. Commonly found in sedimentary basins across Arizona, Madagascar, Brazil, and Indonesia.