fossil

Petrified wood

Silicified wood, commonly quartz (SiO₂) replacing woody tissue

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, gray, and tan with strongly preserved fibrous or bark-like texture; dull to waxy luster and no obvious cleavage. The specimen appears partially mineralized and may retain wood-grain structure, though the image alone cannot confirm composition.

Identified September 22, 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

Buried wood is gradually replaced by silica-rich groundwater during diagenesis, often in volcanic-ash-rich sediments; ages range from millions to hundreds of millions of years. Common deposits include the western United States, Indonesia, Madagascar, and Australia.

Uses & applications

Used as a lapidary material for polished slabs, carvings, cabochons, and display specimens; large intact pieces are collected decoratively rather than used structurally.

Geological facts

Petrified wood is a fossil, not a conventional rock type; quartz can preserve microscopic cellular detail while replacing the original organic matter.

Field identification & locations

Look for continuous wood grain, growth rings, bark texture, very high hardness, and a stone-like weight; a streak or hardness test on an inconspicuous area can help distinguish it from ordinary wood. Typical value is $10–$100 for common pieces, $100–$1,000+ for large, colorful, highly detailed specimens.