mineral

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5–7 on Mohs scale. Color: Brown, tan, and earthy tones with concentric patterns. Luster: Vitreous to waxy. Structure: Cryptocrystalline quartz (Chalcedony) replacing organic cellular structures.

Hardness: 6
Color: Brown, tan, and earthy tones with concentric patterns
Luster: Vitreous to waxy

Identified April 11, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through permineralization over millions of years (often from the Mesozoic or Cenozoic eras). This occurs when organic plant matter is buried by sediment or volcanic ash, and mineral-rich groundwater replaces the woody tissues with silica.

Uses & applications

Used primarily for display specimens, lapidary work (cabochons), jewelry, furniture (table tops), and as a popular item for geological collectors.

Geological facts

Petrified wood is the state gem of Washington, Oregon, and Mississippi. Entire ancient forests, like the one in Arizona's Petrified Forest National Park, have been preserved through this process.

Field identification & locations

Identify by looking for bark-like textures on the exterior and growth rings or wood grain on the interior cross-section. It is commonly found in areas with high volcanic activity or ancient sedimentary basins.