fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5 - 7 on Mohs scale. Color: tan, light brown, yellow, beige. Luster: dull to vitreous. Structure: microcrystalline quartz (chalcedony/jasper) preserving fibrous woody grain structure. Cleavage: none, uneven to conchoidal fracture.

Hardness: 6
Color: tan, light brown, yellow, beige
Luster: dull to vitreous

Identified July 22, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization, where organic wooden tissue buried under sediment or volcanic ash was gradually replaced by dissolved silica (chalcedony/quartz) from groundwater while maintaining the original cellular architecture. Often date from the Devonian through Pleistocene epochs.

Uses & applications

Used for lapidary arts, decorative displays, polished cabochons, carved ornaments, and geological collections.

Geological facts

Petrified wood can retain cellular detail down to microscopic levels, allowing paleobotanists to identify tree species that lived hundreds of millions of years ago, such as extinct conifers and tree ferns.

Field identification & locations

Look for fibrous wood-grain textures, growth rings, and bark-like outer patterns combined with the hardness and density of stone. Commonly found in sedimentary deposits, ancient floodplains, and volcanic ash beds worldwide, such as the Petrified Forest in Arizona.