fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness 6.5-7 on Mohs scale; color ranges from beige, brown, and tan to reddish-yellow; earthy to waxy or vitreous luster; microcrystalline quartz structure maintaining cellular wood grain texture.

Identified July 27, 2026More fossil →

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Physical properties

Hardness 6.5-7 on Mohs scale; color ranges from beige, brown, and tan to reddish-yellow; earthy to waxy or vitreous luster; microcrystalline quartz structure maintaining cellular wood grain texture.

Formation & geological history

Formed through permineralization, where organic wood material is replaced by minerals (primarily chalcedony, quartz, or opal) in dissolved groundwater, typically buried under volcanic ash or sediment over millions of years.

Uses & applications

Used for lapidary crafts, decorative ornaments, jewelry, bookends, furniture tops, and geological display collections.

Geological facts

Petrified wood preserves the original three-dimensional structure of ancient trees down to microscopic cell details, giving scientists valuable info about prehistoric climates and environments.

Field identification & locations

Identified by distinct fibrous wood grain patterns combined with heavy weight and rock-like hardness. Common in Arizona (Petrified Forest National Park), Washington, Madagascar, and Indonesia.