fossil

Petrified wood

Silicified fossil wood, commonly quartz/chalcedony (SiO₂) replacing wood

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, orange, reddish, and tan with visible fibrous wood grain; vitreous to waxy luster and no obvious cleavage. Dense, fine-grained, and often displays quartz or chalcedony filling cellular structure.

Identified September 4, 2026More fossil →

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Physical properties

Formation & geological history

Fossilized wood formed when mineral-rich groundwater replaced organic tissues, typically with silica, while preserving the tree’s anatomy. Most specimens range from Mesozoic to Cenozoic age, though age depends on locality.

Uses & applications

Used as decorative stone, lapidary material, bookends, cabochons, carvings, and collector specimens; unsuitable for ordinary construction aggregate when prized for its patterns.

Geological facts

The original wood is largely replaced by minerals, but growth rings, vessels, and cellular textures can remain remarkably detailed. Iron oxides commonly produce the red, orange, and brown colors.

Field identification & locations

Identify it by preserved wood grain, ring patterns, great density, and hardness; it will not feel or behave like ordinary wood. Common sources include Arizona, Utah, Indonesia, Madagascar, Australia, and Argentina.