sedimentary

Petrified Wood

Silicified wood (primarily quartz, SiO2)

Hardness: 6.5 to 7 on the Mohs scale. Color: Varies widely including tan, brown, white, green, grey, and red depending on mineral impurities. Luster: Vitreous to dull. Crystal structure: Microcrystalline quartz (chalcedony/jasper). Specific gravity: 2.5 to 2.7.

Hardness: 6
Luster: Vitreous to dull

Identified July 31, 2026More sedimentary →

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 when plant material is buried by sediment in an oxygen-depleted environment, preventing decay. Groundwater rich in dissolved minerals flows through the sediment, replacing the organic cellular structure with minerals (usually silica) over millions of years.

Uses & applications

Used in lapidary arts, making decorative objects, jewelry, bookends, and as collectible specimens.

Geological facts

Petrified wood retains the original cellular structure of the ancient tree, sometimes down to microscopic detail, effectively turning living tissue into solid stone.

Field identification & locations

Can be identified in the field by its distinct wood grain and bark textures combined with a stony weight and high hardness. Commonly found in ancient river floodplains, volcanic ash beds, and sedimentary layers worldwide.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Sedimentary Sandstone

Arenite (Sedimentary Rock)

sedimentary

Fossiliferous Concretion

Septarian Concretion containing Brachiopods/Crinoids

fossil

Banded Siltstone / Mudstone Pebble

Siltstone / Argillite

sedimentary

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)

sedimentary

Shale

Shale (clastic sedimentary rock)

sedimentary