fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5 - 7 on Mohs scale. Color: Shades of brown, tan, yellowish-beige, and gray. Luster: Dull to waxy/vitreous. Crystal Structure: Microcrystalline/Cryptocrystalline (Quartz/Chalcedony replacement). Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Shades of brown, tan, yellowish-beige, and gray
Luster: Dull to waxy/vitreous

Identified July 25, 2026More fossil →

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Physical properties

Formation & geological history

Formed via permineralization where organic wood material is replaced by silica minerals (usually quartz or chalcedony) while buried under sediment or volcanic ash, preserving the original cellular structure of the wood over millions of years.

Uses & applications

Used for lapidary arts, gemstone carving, decorative bookends, jewelry, and widely collected by fossil enthusiasts.

Geological facts

Petrified wood preserves the detailed cellular anatomy of the original tree bark and grain. Famous deposits include the Petrified Forest National Park in Arizona, USA.

Field identification & locations

Identify by looking for distinct wood grain patterns, tree rings, or fibrous bark-like textures combined with the hardness, weight, and cool feel of mineralized stone. Common in sedimentary deposits and riverbeds.