fossil

Polished petrified wood

Silicified wood (quartz/chalcedony, SiO₂)

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; tan, brown, amber, and reddish bands with a waxy to vitreous luster. Silica has replaced the original wood cell structure while preserving grain and bark-like textures; no prominent cleavage.

Identified September 21, 2026More fossil →

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Physical properties

Formation & geological history

A fossil formed when buried wood was gradually infiltrated and replaced by silica-rich groundwater, commonly during the Cenozoic or late Mesozoic. Typical environments include volcanic ash beds, floodplains, and sedimentary deposits.

Uses & applications

Used as a lapidary, carving, ornamental, and collectible material; polished pieces are used for cabochons, bookends, and display specimens. It is not generally used as construction stone.

Geological facts

The visible banding and cellular patterns are fossilized wood anatomy, not mineral layering. Color commonly comes from iron, manganese, or other trace elements in the silica.

Field identification & locations

Identify it by preserved wood grain, dense weight, glassy fracture, and hardness sufficient to scratch ordinary glass; an agate-like appearance alone is insufficient. Common sources include Arizona, Oregon, Indonesia, Madagascar, and Australia.