fossil

Petrified Wood

Silicified Wood (primarily SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Cream, tan, and brown banding; Luster: Waxy to vitreous; Structure: Microcrystalline quartz; Cleavage: None; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Cream, tan, and brown banding
Luster: Waxy to vitreous

Identified July 6, 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

Hardness: 6.5-7 on Mohs scale; Color: Cream, tan, and brown banding; Luster: Waxy to vitreous; Structure: Microcrystalline quartz; Cleavage: None; Specific Gravity: 2.6-2.9

Formation & geological history

Formed when plant material is buried by sediment and protected from decay by oxygen and organisms. Groundwater rich in dissolved solids flows through the sediment, replacing the original plant material with silica, calcite, or pyrite over millions of years. This specimen likely dates from the Paleozoic to Cenozoic eras.

Uses & applications

Used for decorative items, jewelry (cabochons), collection display, and scientific study of prehistoric paleobotanical environments.

Geological facts

Arizona's Petrified Forest National Park contains one of the world's largest concentrations of petrified wood. It is a 'pseudomorph' where quartz has taken the form of wood while retaining the original cellular structure.

Field identification & locations

Identified by the preservation of wood-like grain, bark textures, or growth rings in a heavy, stony material. Commonly found in riverbeds or sedimentary basins where ancient forests were once buried.