sedimentary

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Multi-colored with shades of brown, tan, yellow, and grey; Luster: Waxy or vitreous; Crystal structure: Microcrystalline (Cryptocrystalline) quartz; Cleavage: None; Specific gravity: 2.6-2.9

Hardness: 6
Color: Multi-colored with shades of brown, tan, yellow, and grey
Luster: Waxy or vitreous

Identified June 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via permineralization where organic remains are replaced by minerals (usually silica) through groundwater over millions of years. Most common specimens are from the Triassic, Jurassic, or Cenozoic eras.

Uses & applications

Used primarily for ornamental items, jewelry (cabochons), interior design (tabletops/bookends), and as educational museum specimens.

Geological facts

Even though it is made of stone, the cellular structure of the original tree is often preserved in incredible detail, allowing paleobotanists to identify the species of the ancient tree.

Field identification & locations

Identify in the field by looking for wood-grain patterns, bark textures, or growth rings in a heavy, stony material. Commonly found in arid regions like Arizona (Petrified Forest National Park) and Washington state.