sedimentary
Petrified Wood
Silicified Wood (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Tan, brown, and grey with possible reddish hints; Luster: Waxy to vitreous; Crystal structure: Usually cryptocrystalline (microscopic quartz); Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Tan, brown, and grey with possible reddish hints
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Tan, brown, and grey with possible reddish hints; Luster: Waxy to vitreous; Crystal structure: Usually cryptocrystalline (microscopic quartz); Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the process of permineralization where organic wood materials are replaced by minerals (usually silica) over millions of years, typically in volcanic ash or river sedimentary environments from the Triassic through Cenozoic eras.
Uses & applications
Used for jewelry (cabochons), interior decoration (tables, bookends), and highly sought after by geological collectors.
Geological facts
Arizona's Petrified Forest National Park contains one of the world's largest and most colorful concentrations of petrified wood. It is essentially a fossil that has turned completely to stone.
Field identification & locations
Identify in the field by looking for cellular wood structures, growth rings, or bark textures preserved in stone. Found globally in areas with ancient fossilized forests like the USA, Argentina, and Egypt.
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