sedimentary

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Red, brown, tan, and white; Luster: Vitreous to waxy; Structure: Microcrystalline quartz (Chalcedony/Agate) replacing organic cellular structure; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Red, brown, tan, and white
Luster: Vitreous to waxy

Identified May 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via permineralization where organic plant matter is buried by sediment (often volcanic ash) and replaced by minerals—typically silica—from groundwater over millions of years, often dating to the Triassic or Cenozoic periods.

Uses & applications

Used for ornamental purposes, lapidary arts, high-end furniture (slabs), jewelry (cabochons), and as museum or private collector specimens.

Geological facts

The Petrified Forest National Park in Arizona contains one of the world's largest concentrations of petrified wood. These specimens are actual fossils where every cell of the original tree has been replaced by stone while maintaining the tree's original shape.

Field identification & locations

Identify in the field by looking for bark-like textures or rings on the exterior and smooth, glass-like (conchoidal) fractures on the interior. Commonly found in areas with ancient volcanic activity and sedimentary basins.