fossil

Petrified Wood

Silicified wood (primarily quartz, SiO2)

Mohs hardness of 7, colors range from brown, red, and yellow to gray and black, vitreous to waxy luster, amorphous crystal structure (cryptocrystalline quartz/chalcedony), conchoidal fracture, specific gravity around 2.5-2.7

Identified August 4, 2026More fossil →

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Physical properties

Formation & geological history

Formed when buried wood is slowly replaced by minerals (usually silica) over millions of years through permineralization, often dating from the Triassic period or older

Uses & applications

Used for ornamental carvings, polished display specimens, lapidary art, jewelry, and by collectors

Geological facts

Famous locations include the Petrified Forest National Park in Arizona; the original cellular structure of the wood is often preserved microscopically

Field identification & locations

Identify by the preservation of tree rings, bark texture, or wood grain combined with a stony weight and rock-like hardness; commonly found in sedimentary rock layers associated with ancient floodplains and volcanic ash

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