fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Tan, brown, reddish-orange; Luster: Dull to waxy; Structure: Microcrystalline quartz (chalcedony) preserving organic cellular structures; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Tan, brown, reddish-orange
Luster: Dull to waxy

Identified July 13, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization over millions of years (typically Mesozoic or Cenozoic). Organic material is replaced by minerals, usually silica, while buried under sediment or volcanic ash.

Uses & applications

Used for ornamental carvings, jewelry (lapidary), decorative bookends, furniture tops, and as a popular geological collectible.

Geological facts

Petrified wood can preserve details down to the microscopic level, allowing paleobotanists to identify the specific species of the original tree. Arizona's Petrified Forest National Park contains some of the world's most famous deposits.

Field identification & locations

Identify by a bark-like texture on the exterior and visible growth rings or wood grains. Often feels much heavier and cooler to the touch than dry wood. Found in areas with historical volcanic activity and sedimentary basins.