mineral

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Red, brown, tan, and orange due to iron oxides; Luster: Vitreous to waxy; Crystal structure: Microcrystalline (trigonal); Cleavage: None/Conchoidal fracture; Specific gravity: 2.6-2.9

Hardness: 6
Color: Red, brown, tan, and orange due to iron oxides
Luster: Vitreous to waxy

Identified February 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed through permineralization where organic wood materials are replaced by silica (chalcedony or quartz) over millions of years, often in volcanic ash beds or sedimentary basins dating from the Paleozoic to Cenozoic eras.

Uses & applications

Used primarily for jewelry (cabochons), interior decoration (tabletops, bookends), and as a popular lapidary material for collectors.

Geological facts

Petrified wood is the state gemstone of Washington and Mississippi. The most famous location is the Petrified Forest National Park in Arizona, which contains logs that are over 225 million years old.

Field identification & locations

Identify by looking for visible growth rings, bark patterns, or wood cellular structures preserved in stone. Commonly found in riverbeds or badlands. Collectors look for high color saturation and preservation of detail.

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