sedimentary
Petrified Wood
Silicified wood (SiO2 - Silicon Dioxide)
Hardness: 6.5–7 (Mohs scale); Color: Gray, brown, charcoal; Luster: Waxy to dull; Characterized by preserved wood grain texture and ring structures.
- Hardness
- 6
- Color
- Gray, brown, charcoal
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Gray, brown, charcoal; Luster: Waxy to dull; Characterized by preserved wood grain texture and ring structures.
Formation & geological history
Formed through permineralization where organic wood material is replaced by minerals, typically quartz or opal, in anaerobic conditions such as volcanic ash or fluvial sediments. Most specimens range from several million to hundreds of millions of years old.
Uses & applications
Used for architectural decoration, furniture (tabletops), jewelry (cabs), and as a popular terrestrial fossil for collectors.
Geological facts
In some cases, the replacement is so perfect that cell structures are visible under a microscope. Arizona's Petrified Forest National Park contains one of the world's largest concentrations of this material.
Field identification & locations
Identify by looking for visible growth rings, bark textures, and woody grain patterns coupled with a stony, heavy feel. Common in areas with a history of volcanic activity and ancient floodplains.
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