fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness of 7 on the Mohs scale, varying colors including brown, yellow, red, and black, waxy to vitreous luster, amorphous crystal structure (microcrystalline quartz/chalcedony), conchoidal fracture, specific gravity around 2.5-2.7

Identified August 1, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization where organic material is buried in an oxygen-depleted environment under sediment and gradually replaced by minerals like silica-rich groundwater over millions of years (often dating back to the Triassic period or earlier)

Uses & applications

Used in ornamental carvings, lapidary art, jewelry, high-end home decor, and as collectible museum or display specimens

Geological facts

Petrified wood retains the original cellular structure of the ancient tree while completely transforming into stone, allowing scientists to study prehistoric ecosystems and ancient climates

Field identification & locations

Can be identified in the field by its distinct tree-ring or bark-like exterior combined with a heavy, stone-like feel and a smooth, vitreous fracture showing grain; commonly found in areas with ancient volcanic ash deposits or river floodplains such as the Petrified Forest in Arizona