fossil

Petrified Wood

Silicified wood (primarily quartz, SiO2)

Hardness of 6.5-7 on the Mohs scale, colors vary widely including brown, red, yellow, and black due to mineral impurities, luster ranges from vitreous to dull, crystal structure is microcrystalline quartz (chalcedony or jasper).

Identified August 5, 2026More fossil →

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Physical properties

Formation & geological history

Formed when plant material is buried in an oxygen-free environment under sediment, where mineral-rich water flowing through the sediment replaces the organic wood structure with minerals like silica over millions of years.

Uses & applications

Used in ornamental items, high-end lapidary work, jewelry, tabletops, and as a collectible specimen.

Geological facts

Petrified wood can preserve the cellular structure of the original tree in exquisite detail, sometimes even retaining microscopic cell walls.

Field identification & locations

Can be identified by weight (much heavier than normal wood), the presence of visible growth rings combined with a stony texture, and a conchoidal fracture. Found worldwide in sedimentary deposits, notably in places like the Petrified Forest National Park in Arizona.

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