fossil

Petrified Wood

Silicified wood (primarily SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Tan, brown, orange, and reddish hues due to iron oxides; Luster: Vitreous to waxy; Structure: Microcrystalline quartz (chalcedony) preserving organic cellular structures; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Tan, brown, orange, and reddish hues due to iron oxides
Luster: Vitreous to waxy

Identified July 8, 2026More fossil →

Explore Petrified Wood in the encyclopedia →

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 where organic wood materials are replaced by minerals (usually silica) over millions of years. This specimen likely dates back to the Mesozoic or Cenozoic eras and formed in an environment with volcanic ash and ground water.

Uses & applications

Used primarily for lapidary work, jewelry, interior decor (tabletops, bookends), and as collector specimens for geological interest.

Geological facts

Petrified wood is the state stone of Arizona; the process preserves details down to the microscopic level, including tree rings and bark patterns. In some cases, precious stones like opal can replace the wood fibers.

Field identification & locations

Identify in the field by looking for bark textures, growth rings, and wood-like grain in a heavy, stony material that cannot be scratched by a steel knife. Common in areas with sedimentary deposits like the Petrified Forest National Park region.