sedimentary

Petrified Wood

Silicified Wood (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, grey, black; Luster: Dull to vitreous/glassy; Crystal structure: Microcrystalline or amorphous (Quartz/Chalcedony); Cleavage: None; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Brown, tan, grey, black
Luster: Dull to vitreous/glassy

Identified June 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through permineralization when woody plant material is buried in sediment and organic matter is replaced by minerals, typically silicates, from groundwater over millions of years (often Triassic or Cenozoic).

Uses & applications

Used for decorative items, jewelry (cabochons), furniture (tabletops), and highly valued as geological collectibles.

Geological facts

The cell structure of the wood is often preserved in such detail that the original tree species can be identified microscopically; the 'Petrified Forest National Park' in Arizona is one of the most famous sites.

Field identification & locations

Identified by wood-like textures such as bark patterns or growth rings combined with a stony, heavy, and hard mineral feel. Common in areas with volcanic ash and ancient riverbeds.