fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: reddish-brown, tan, and orange hues due to iron oxides; Luster: waxy to vitreous; Structure: preserves original cellular tree bark and ring structures; Cleavage: none, conchoidal fracture

Hardness: 6
Color: reddish-brown, tan, and orange hues due to iron oxides
Luster: waxy to vitreous

Identified July 25, 2026More fossil →

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Physical properties

Formation & geological history

Formed when plant material is buried by sediment and protected from decay due to oxygen deprivation. Mineral-rich water flowing through the sediment deposits silica, chalcedony, or quartz into the plant's cells, replacing organic matter over millions of years.

Uses & applications

Used for ornamental carvings, lapidary projects, cabochons for jewelry, and highly popular as display specimens for fossil collectors.

Geological facts

The process of petrifaction turns organic wood completely into stone while retaining its original microscopic structure. Famous locations include the Petrified Forest National Park in Arizona, USA.

Field identification & locations

Identified by distinct woody grain, bark textures, and growth rings combined with the hardness and density of chalcedony/quartz. Commonly found in sedimentary rock layers, volcanic ash beds, and gravel deposits.