fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5 to 7 on the Mohs scale, Color: varies widely including brown, grey, white, red, and yellow, Luster: vitreous to dull, Crystal structure: microcrystalline quartz (chalcedony/jasper), Cleavage: none (conchoidal fracture), Specific gravity: 2.5 to 2.7

Hardness: 6

Identified August 3, 2026More fossil →

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Physical properties

Formation & geological history

Formed when organic plant material is buried in an oxygen-depleted environment (such as volcanic ash or sedimentary mud) and groundwater rich in dissolved silica slowly replaces the original cellular structure with minerals over millions of years.

Uses & applications

Used in lapidary arts, ornamental objects, high-end furniture, bookends, jewelry, and prized by fossil and mineral collectors.

Geological facts

Petrified wood can preserve microscopic cellular structures of ancient trees dating back hundreds of millions of years, allowing scientists to study prehistoric ecosystems.

Field identification & locations

Identified by the retention of tree-like grain and bark textures combined with a heavy, stone-like feel and high hardness. Common in regions with ancient volcanic activity or extensive sedimentary layers like the Petrified Forest National Park in Arizona.