fossil

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Variegated shades of gray, white, blue, and brown; Luster: Vitreous to waxy; Structure: Microcrystalline quartz maintaining botanical cell structures; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Variegated shades of gray, white, blue, and brown
Luster: Vitreous to waxy

Identified July 14, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization, a process where organic material is replaced by minerals (usually silica) from groundwater while buried in sediment or volcanic ash. This specimen likely dates from the Paleozoic to Cenozoic eras.

Uses & applications

Used for ornamental decoration, lapidary work (cabbing), furniture (large slabs), jewelry, and as educational/museum specimens.

Geological facts

Petrified wood is the state fossil of Washington, Arizona, and several other states. In some cases, the replacement is so perfect that tree rings and even microscopic cellular structures are preserved.

Field identification & locations

Identify by looking for bark-like textures on the exterior and growth-ring patterns on the cross-section. Commonly found in areas with past volcanic activity that provided silica-rich ash, such as the Petrified Forest National Park in Arizona.

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