fossil
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of organic matter)
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, cream, and gray; Luster: Dull to waxy; Structure: Maintains original cellular structure of wood; Specific Gravity: 2.6-2.9.
- Hardness
- 6
- Color
- Brown, tan, cream, and gray
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, cream, and gray; Luster: Dull to waxy; Structure: Maintains original cellular structure of wood; Specific Gravity: 2.6-2.9.
Formation & geological history
Formed when plant material is buried by sediment and protected from decay by organisms and oxygen. Groundwater rich in dissolved solids (silica) flows through the sediment, replacing the original plant material with silica. Most common in volcanic ash deposits, often dating from various periods like the Triassic to the Cenozoic.
Uses & applications
Used primarily for decorative purposes, lapidary art, jewelry, furniture (such as table tops), and as collector specimens.
Geological facts
Arizona's Petrified Forest National Park contains one of the world's largest and most colorful concentrations of petrified wood. It is technically a fossil, where the wood has been turned to stone.
Field identification & locations
Identify in the field by looking for bark textures, growth rings, and wood grain in a rock that is much heavier and harder than actual wood. Common in the Western United States, Madagascar, and Brazil.
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