fossil

Petrified wood

Silicified wood, commonly quartz/chalcedony (SiO₂) replacing woody tissue

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, reddish, black, and gray coloration with visible fibrous wood grain. Usually dull to waxy or slightly glassy, dense, with quartz microcrystals and no prominent cleavage; specific gravity about 2.4–2.7.

Identified September 13, 2026More fossil →

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Physical properties

Formation & geological history

Fossilized wood formed when buried logs were infiltrated and gradually replaced by silica-rich groundwater, preserving cellular structure; most examples range from Paleozoic to Cenozoic age. The specimen appears rough-cut or naturally fractured, with strong longitudinal wood texture.

Uses & applications

Used for lapidary slabs, cabochons, carvings, ornaments, and collector specimens; exceptionally colorful material is used in jewelry and polished decor.

Geological facts

Unlike ordinary wood, petrified wood commonly rings or produces a sharp porcelain-like sound when tapped. Iron oxides create red and orange colors, while manganese or carbon can produce dark tones.

Field identification & locations

Identify it by preserved bark, growth rings, pores, and wood grain combined with stone-like weight and hardness; common sources include Arizona, Utah, Oregon, Indonesia, Madagascar, and Australia.