sedimentary

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 (Mohs). Color: Grey, brown, tan. Luster: Dull to waxy. Structure: Preserved woody cellular structure replaced by cryptocrystalline quartz. Specific gravity: 2.6-2.9.

Hardness: 6
Color: Grey, brown, tan
Luster: Dull to waxy

Identified June 20, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs). Color: Grey, brown, tan. Luster: Dull to waxy. Structure: Preserved woody cellular structure replaced by cryptocrystalline quartz. Specific gravity: 2.6-2.9.

Formation & geological history

Formed through permineralization over millions of years (often Triassic or Jurassic) when organic wood is buried under sediment and volcanic ash, and silica-rich groundwater replaces the cells with minerals.

Uses & applications

Used for decorative masonry, high-end furniture (slabs), lapidary art, jewelry, and as a popular collectable for geological study.

Geological facts

Depending on the minerals present, petrified wood can feature brilliant colors: iron produces reds and oranges, while manganese produces pinks and blacks. Large forests like Petrified Forest National Park contain entire logs preserved in stone.

Field identification & locations

Identify by looking for growth rings, bark textures, and woody grain in a stone that is too hard to be scratched by a steel knife. Commonly found in arid sedimentary basins and volcanic regions.