Sedimentary / Fossil

Petrified Wood

Fossilized wood / Silicified wood

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Brown, tan, reddish, grey, yellow, Luster: Waxy to dull, Crystal structure: Microcrystalline quartz (chalcedony/opal/agate replacing wood), Cleavage: None (conchoidal fracture), Specific gravity: 2.58-2.91

Hardness: 6

Identified June 9, 2026More sedimentary / 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. 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.

Uses & applications

Used in lapidary arts, jewelry, collecting, interior decor, and scientific study of paleoenvironments.

Geological facts

Petrified wood can preserve the original cell structure of the wood down to the microscopic level. Famous locations include the Petrified Forest National Park in Arizona.

Field identification & locations

Identify by looking for wood-like grain and bark textures that are heavy and hard like stone. Often found in sedimentary rock formations, especially those related to ancient floodplains or volcanic ash deposits.

Other sedimentary / fossil specimens

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Ammonite fossil

Fossilized ammonoid cephalopod; likely an involute ammonite, exact genus/species indeterminate

fossil

Likely polished/tumbled fossil shell or concretion

Indeterminate; possibly a fossil bivalve or gastropod in mineralized matrix

fossil

Chalcedony (Tumbled)

Silicon Dioxide (SiO2)

mineral

Vesicular basalt (possibly amygdaloidal basalt)

Basalt, a mafic volcanic rock composed mainly of plagioclase feldspar, pyroxene, and commonly olivine; cavities may contain secondary zeolites, calcite, or quartz.

igneous

Dinosaur Claw Fossil

Fossilized Theropod Claw (Vertebrate Palaeontological Specimen)

fossil

Polished fossil shell or bone fragment (tentative)

Indeterminate biogenic carbonate or fossilized bone; possibly a small gastropod/bivalve fragment

fossil