sedimentary

Petrified Wood

Silicified Wood (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Brown, tan, reddish-brown, Luster: Vitreous to dull, Crystal structure: Cryptocrystalline (chalcedony/quartz), Specific Gravity: 2.6-2.9

Hardness: 6

Identified June 6, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Brown, tan, reddish-brown, Luster: Vitreous to dull, Crystal structure: Cryptocrystalline (chalcedony/quartz), Specific Gravity: 2.6-2.9

Formation & geological history

Formed via permineralization where organic wood materials are replaced by minerals (usually silica) while retaining original structure; commonly from the Triassic to Cenozoic eras in sedimentary environments like river basins and volcanic ash beds.

Uses & applications

Used in ornamental lapidary work, jewelry (cabochons), decorative furniture (tables), and as highly sought-after display specimens for collectors.

Geological facts

The process preserves the microscopic details of the wood such as tree rings and cell structure. The presence of trace elements like manganese or iron creates the vibrant colors. Arizona's Petrified Forest National Park contains one of the world's largest concentrations.

Field identification & locations

Identify by looking for wood-like grain patterns, tree rings, or bark textures on a stone that is much heavier than wood and cannot be scratched by a steel knife. Common in the Western US, Madagascar, and Indonesia.