mineral

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7.0 on Mohs scale; Color: Variable (brown, tan, black, grey, red); Luster: Vitreous to waxy; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.9

Hardness: 6
Color: Variable (brown, tan, black, grey, red)
Luster: Vitreous to waxy

Identified June 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed through permineralization where organic wood materials are replaced by minerals (usually silica) over millions of years. This specimen often dates from the Triassic, Jurassic, or Cretaceous periods.

Uses & applications

Used for jewelry (cabochons), interior decor (tabletops, bookends), and as collector specimens in mineralogy and paleontology.

Geological facts

Petrified wood is the state gem of Washington and the state fossil of Arizona. It preserves the microscopic cellular structure of the original tree despite being entirely stone.

Field identification & locations

Identify by looking for bark textures and growth rings preserved in stone. Found globally in ancient sedimentary basins like Arizona's Petrified Forest or the Egyptian deserts. Collectors look for high polish and vibrant color retention.