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 of 2.5 to 2.7

Identified August 5, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization, where organic wood material is completely replaced by minerals (usually silicates like quartz) over millions of years, often dating from the Triassic period or earlier (millions of years old)

Uses & applications

Used in ornamental carvings, jewelry, lapidary art, tabletops, and highly prized by fossil and rock collectors

Geological facts

Petrified wood retains the original cellular structure of the tree while turning entirely to stone. The Petrified Forest National Park in Arizona is one of the most famous localities in the world for these specimens.

Field identification & locations

Can be identified in the field by its distinct tree-ring patterns, bark texture, and high density/hardness characteristic of quartz, commonly found in sedimentary rock layers associated with ancient volcanic ash or flood plains