fossil

Petrified Wood

Silicified wood (Quartz replacement)

Hardness of 7 on the Mohs scale, colors ranging from brown, tan, and red to yellow and black depending on mineral impurities, vitreous to dull luster, amorphous crystal structure of microcrystalline quartz (chalcedony/jasper), conchoidal fracture, specific gravity around 2.6 - 2.7

Identified July 28, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization when fallen trees are buried by sediment in an anoxic environment, preventing decay, and groundwater rich in dissolved silica slowly replaces the organic wood tissue with stone over millions of years, dating from the Triassic period and older

Uses & applications

Used in lapidary arts, making decorative items, jewelry, bookends, table tops, and as collector specimens

Geological facts

Petrified wood can preserve microscopic cellular structures of ancient trees, allowing scientists to identify prehistoric plant species millions of years old

Field identification & locations

Can be identified in the field by its distinct wood-like exterior texture combined with a heavy stone weight and conchoidal fracture showing quartz or chalcedony internally; found worldwide, notably in the Petrified Forest National Park in Arizona