Rock Identifier
Petrified Wood (Silicified Wood (primarily SiO2)) — fossil
fossil

Petrified Wood

Silicified Wood (primarily SiO2)

AI-generated identification · may be incorrect

Hardness 6.5-7 on Mohs scale; color ranges from yellow-brown, tan, to deep dark brown; dull to vitreous or waxy luster; retains preserved fibrous wood grain structure; no cleavage; fracture is conchoidal to splintery.

Identified More fossil →
Explore Petrified Wood in the encyclopedia →

Identify your own rocks.

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

App StoreGoogle Play

Physical properties

Hardness 6.5-7 on Mohs scale; color ranges from yellow-brown, tan, to deep dark brown; dull to vitreous or waxy luster; retains preserved fibrous wood grain structure; no cleavage; fracture is conchoidal to splintery.

Formation & geological history

Formed when fallen trees are buried rapidly under sediment or volcanic ash, saturated with mineral-rich groundwater. Over millions of years, silica replaces the organic cellular matter through permineralization, preserving internal structures.

Uses & applications

Used extensively in lapidary arts, decorative displays, carved ornaments, cabochons, tabletop manufacturing, and as popular fossil collection specimens.

Geological facts

Some petrified wood specimens preserve cellular structures so perfectly that individual tree rings and cell walls can be identified under a microscope. Entire petrified forests exist worldwide, such as the Petrified Forest National Park in Arizona.

Field identification & locations

Look for distinct wood grain patterns, tree ring structures, or bark textures combined with the weight and hardness of stone or chalcedony. Common in sedimentary beds, volcanic deposits, and river gravels.

More like this

Other fossil specimens

Probable fossil-bearing rock or mineral concretion (Unidentified carbonate-rich concretion with a possible fossil inclusion) — fossil

Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

fossil
Likely fossil oyster shell (Fossilized bivalve shell; exact species cannot be identified from the image) — fossil

Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

fossil
Crinoid Stem Fossil in Matrix (Phylum Echinodermata, Class Crinoidea) — fossil

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

fossil
Fossiliferous limestone (likely a crinoidal or shell-fragment limestone) (Bioclastic limestone, composed chiefly of calcite (CaCO₃)) — sedimentary

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

sedimentary
Rounded sedimentary pebble (Likely micritic limestone or calcareous sandstone) — sedimentary

Rounded sedimentary pebble

Likely micritic limestone or calcareous sandstone

sedimentary
Chert with Fossil Brachiopod (Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion) — sedimentary

Chert with Fossil Brachiopod

Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion

sedimentary