fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 (Mohs), Color: rich browns, oranges, reds, and yellows from iron and manganese oxides, Luster: waxy to vitreous when polished, Structure: microcrystalline quartz (chalcedony) with preserved cellular plant structure.

Hardness: 6

Identified July 10, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization over millions of years (often Carboniferous to Triassic periods), where organic wood material is replaced by silica-rich groundwater while buried under sediment or volcanic ash.

Uses & applications

Ornamental jewelry, lapidary art, home decor, and educational/scientific study of ancient paleobotany.

Geological facts

Arizona's Petrified Forest National Park contains trees that are over 225 million years old. Even though it is now stone, the growth rings and bark texture are often perfectly preserved down to the microscopic level.

Field identification & locations

Identify by looking for wood-like grain patterns, knots, or rings within a very hard stony material that cannot be scratched by a steel pocket knife. Found globally in ancient sedimentary basins.