fossil

Petrified wood

Silicified fossil wood, commonly quartz/chalcedony (SiO₂)

AI-generated identification · may be incorrect

Brown, black, and tan woody banding with a fibrous grain-like texture; typically hardness 6.5–7, vitreous to dull luster, very low porosity, and no true cleavage. The specimen appears polished or naturally smoothed.

Identified September 11, 2026More fossil →

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Physical properties

Formation & geological history

Mineral-rich groundwater replaced the original wood cell by cell, usually with silica, during burial; it commonly formed in volcanic-ash-rich sediments over millions of years, from the Triassic onward.

Uses & applications

Used as a decorative stone, cabochons, bookends, carvings, and collector specimens; durable pieces may be slabbed and polished.

Geological facts

Cell structures and growth rings can remain visible despite complete mineral replacement. Black coloration may reflect manganese or carbon, while brown and red tones commonly reflect iron oxides.

Field identification & locations

Identify it by preserved wood grain, ring patterns, heavy weight, and a glassy fracture or silica-rich hardness; common sources include Arizona, Oregon, Indonesia, Madagascar, and Argentina.