fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness of 7 on the Mohs scale, colors ranging from brown, red, and yellow to gray and white, vitreous to waxy luster, amorphous crystal structure (microcrystalline quartz/chalcedony), no cleavage, specific gravity of 2.6 to 2.7

Identified August 7, 2026More fossil →

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Physical properties

Formation & geological history

Formed when organic plant material is buried in an anoxic, mineral-rich environment (such as volcanic ash or river sediments) and groundwater rich in dissolved silica slowly replaces the cellular structure of the wood with minerals over millions of years.

Uses & applications

Used for ornamental carvings, polished display specimens, jewelry, lapidary arts, and scientific study of prehistoric forests.

Geological facts

Petrified wood can preserve microscopic cellular structures of ancient trees dating back hundreds of millions of years, often from the Triassic period or older.

Field identification & locations

Identified in the field by its distinct wood-like grain and texture combined with a stone-like weight, hardness, and cold feel. Commonly found in desert regions, ancient floodplains, and areas with historic volcanic activity such as Arizona, USA.