fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness 6.5-7 on Mohs scale, earthy brown to reddish tone with distinct parallel grain patterns, vitreous to waxy luster, conchoidal fracture, microcrystalline quartz structure, specific gravity around 2.6-2.8.

Identified July 27, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization when organic plant matter is buried rapidly under sediment or volcanic ash, excluding oxygen. Over time, silica-rich groundwater replaces the cellular structure with chalcedony or jasper while retaining the original woody texture.

Uses & applications

Used widely for lapidary arts, tumbled stones, decorative ornaments, bookends, jewelry cabochons, and scientific/educational collections.

Geological facts

Petrified wood can retain cellular-level detail of the original ancient tree, including tree rings and bark textures. Famous deposits include the Petrified Forest National Park in Arizona, USA.

Field identification & locations

Identified by its distinctive wood-like grain and fibrous pattern combined with the weight, hardness, and cold feeling of solid chalcedony/jasper rock. Common in alluvial gravel deposits and sedimentary basins worldwide.