fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness of 7 on the Mohs scale; colors include brown, red, yellow, and grey; vitreous to dull luster; amorphous quartz structure.

Identified October 30, 2026More fossil →

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Physical properties

Hardness of 7 on the Mohs scale; colors include brown, red, yellow, and grey; vitreous to dull luster; amorphous quartz structure.

Formed when buried wood is slowly replaced by silica-rich groundwater over millions of years, typically dating from the Triassic period onward.

Used in lapidary arts, decorative carvings, jewelry making, and as educational collector specimens.

Famous occurrences include the Petrified Forest National Park in Arizona, where entire ancient ecosystems are preserved in stone.

Identified by maintaining the distinct cellular structure, growth rings, and bark texture of original wood despite being solid rock.

Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

Likely fossil oyster shell

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

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image