fossil

Petrified Wood

Silicified Wood (SiO2-dominant)

Hardness: 6.5-7 (Mohs); Color: Brown, red, tan, orange due to iron impurities; Luster: Dull to waxy; Structure: Preservation of original cellular plant structure through permineralization; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Brown, red, tan, orange due to iron impurities
Luster: Dull to waxy

Identified July 6, 2026More fossil →

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Physical properties

Formation & geological history

Organic plant matter buried under sediment or volcanic ash. Over millions of years, groundwater rich in dissolved minerals (like silica) fills the cells, turning the wood into stone while maintaining the tree's structure. Often dates from the Paleozoic to the Cenozoic eras.

Uses & applications

Used for decorative lapidary work, jewelry (cabochons), bookends, furniture slices, and as a popular collector's specimen.

Geological facts

Arizona's Petrified Forest National Park contains one of the world's largest concentrations of petrified wood, mostly from the Triassic period (about 225 million years ago). Different colors represent different minerals: Iron produces reds/yellows, while Manganese produces purples/blacks.

Field identification & locations

Identify by looking for radial wood grain, tree rings, bark-like textures, and a stone-like hardness that cannot be scratched by a steel knife. Commonly found in areas with historical volcanic activity and sedimentary basins.