fossil
Petrified Wood
Silicified Wood (primarily Quartz/SiO2)
Hardness: 6.5-7 Mohs; Color: Tan, brown, grey, and cream with visible growth rings; Luster: Vitreous to waxy; Lacks cleavage; Conchoidal fracture common in agatized areas.
- Hardness
- 6
- Color
- Tan, brown, grey, and cream with visible growth rings
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Tan, brown, grey, and cream with visible growth rings; Luster: Vitreous to waxy; Lacks cleavage; Conchoidal fracture common in agatized areas.
Formation & geological history
Formed through permineralization when woody plant material is buried by sediment (often volcanic ash) and water-borne minerals seperti silica replace the organic cell structure over millions of years, typically ranging from the Devonian to the Holocene periods.
Uses & applications
Used for ornamental carvings, jewelry (cabochons), furniture tops, and highly prized by fossil and mineral collectors as display specimens.
Geological facts
Petrified wood is the state fossil of Washington and Arizona. While the organic matter is gone, the internal structure like bark and growth rings are often perfectly preserved down to the cellular level.
Field identification & locations
Identify by looking for distinct concentric rings similar to tree cross-sections and wood-grain textures on a heavy, stone-like material. It is commonly found in sedimentary beds near volcanic regions like Arizona's Petrified Forest or the Ginkgo Petrified Forest in Washington.
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