fossil

Petrified Wood

Silicified Wood (SiO2 permineralization)

Hardness: 6.5-7.0 (Mohs scale); Color: Brown, tan, reddish, and cream; Luster: Waxy to vitreous; Structure: Preserves cellular plant structure in cryptocrystalline quartz; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Brown, tan, reddish, and cream
Luster: Waxy to vitreous

Identified July 13, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization where organic wood materials are replaced by minerals (usually silica) over millions of years, typically occurring when trees are buried under sediment or volcanic ash. These specimens often date back to the Triassic or Neogene periods.

Uses & applications

Used for decorative ornaments, desktop specimens, lapidary art, jewelry, and as educational geological samples for collectors.

Geological facts

Petrified wood is the state gemstone of Washington and the state fossil of Arizona. Large concentrations can be found in the Petrified Forest National Park, where trees fallen 225 million years ago were turned to stone.

Field identification & locations

Identify by looking for bark textures and growth rings on the exterior with a stony, heavy weight. Common in areas with ancient volcanic activity and sedimentary basins like Arizona, Oregon, and Madagascar.

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