fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness of 7 on the Mohs scale, vitreous to dull luster, preserves cellular wood structure with cryptocrystalline quartz replacement.

Identified November 3, 2026More fossil →

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Physical properties

Hardness of 7 on the Mohs scale, vitreous to dull luster, preserves cellular wood structure with cryptocrystalline quartz replacement.

Formed when buried wood is slowly replaced by silica-rich groundwater over millions of years, commonly in sedimentary basins.

Used in decorative items, jewelry, high-end lapidary work, and sought after by fossil and mineral collectors.

The organic material is completely replaced by minerals while retaining the exact microscopic structure of the original wood.

Identify by visible growth rings and bark texture combined with extreme hardness and conchoidal fracture of quartz; found worldwide.

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