fossil

Petrified Wood

Silicified Wood (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: earthy tones including brown, yellow, red, black, and gray, Luster: dull to waxy depending on polish, Crystal structure: microcrystalline (cryptocrystalline), Cleavage: none, Specific gravity: 2.6-2.8

Hardness: 6

Identified September 21, 2026More fossil →

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Physical properties

Formation & geological history

Formed when plant material is buried by sediment and protected from decay due to oxygen deprivation and organisms. Groundwater rich in dissolved solids flows through the sediment, replacing the original plant material with silica, calcite, pyrite, or another inorganic material such as opal. This process can take millions of years.

Uses & applications

Used in jewelry, lapidary arts, ornamental objects, and collected as specimens.

Geological facts

Petrified wood is the state fossil of Washington and North Dakota. The Petrified Forest National Park in Arizona is famous for its large concentrations of highly colorful petrified wood.

Field identification & locations

Identified by the preservation of original woody structure (like tree rings or bark texture), hardness (scratches glass if silicified), and heaviness compared to regular wood. Found globally in sedimentary deposits of various geological ages. Tips for collectors: look for pieces with distinct wood grain and vibrant colors.