sedimentary
Petrified Wood
Silicified Wood (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, cream, gray; Luster: Vitreous to waxy; Crystal structure: Amorphous/Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6-2.9.
- Hardness
- 6
- Color
- Brown, tan, cream, gray
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, cream, gray; Luster: Vitreous to waxy; Crystal structure: Amorphous/Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6-2.9.
Formation & geological history
Formed through permineralization where organic wood materials are replaced by silicate minerals (usually chalcedony or opal) over millions of years. This specimen likely dates back to the Triassic or Cenozoic periods.
Uses & applications
Used primarily for jewelry (cabochons), lapidary art, furniture details, and as a popular collector's specimen.
Geological facts
In petrified wood, the original cellular structure of the tree is often perfectly preserved despite being entirely stone. The colors are caused by trace elements: iron produces reds/browns, while manganese produces pinks/oranges.
Field identification & locations
Identify by looking for wood-grain patterns, growth rings, or bark textures on the exterior. Common in the Western United States (Arizona, Washington) and Madagascar.
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