mineral

Petrified Wood

Silicified Wood (primarily Silicon Dioxide, SiO2)

Hardness: 7.0 on Mohs scale; Color: Multi-colored (reds, browns, yellows, tans); Luster: Vitreous to waxy; Structure: Cryptocrystalline (replacing organic cellular structure); Cleavage: None (conchoidal fracture).

Hardness: 7
Color: Multi-colored (reds, browns, yellows, tans)
Luster: Vitreous to waxy

Identified March 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed through permineralization over millions of years (often Triassic, 200-250 million years ago) when wood is buried in sediment or volcanic ash, and mineral-rich groundwater replaces organic matter with silica.

Uses & applications

Used for ornamental furniture (tabletops), lapidary work, jewelry, and as highly prized geological display specimens.

Geological facts

Trace elements determine the colors: iron creates reds and yellows, manganese creates pinks and blacks, and cobalt or copper creates blues and greens. Arizona's Petrified Forest is one of the world's most famous sites.

Field identification & locations

Identify in the field by looking for bark-like textures or growth rings on the exterior of stones that feel significantly heavier than wood. Common in the USA (Arizona, Oregon), Madagascar, and Indonesia.

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