sedimentary
Petrified Wood (Agatized/Silicified Wood)
Silicified Wood (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Dark brown to black, Luster: Vitreous to dull, Crystal Structure: Cryptocrystalline (Microcrystalline Quartz), Cleavage: None, Specific Gravity: 2.6-2.9
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Dark brown to black, Luster: Vitreous to dull, Crystal Structure: Cryptocrystalline (Microcrystalline Quartz), Cleavage: None, Specific Gravity: 2.6-2.9
Formation & geological history
Formed via permineralization where organic plant matter is replaced by silica minerals (usually chalcedony or quartz) over millions of years in anaerobic sedimentary environments. This specimen likely dates back to the Triassic or Jurassic period.
Uses & applications
Used in jewelry (lapidary), ornamental furniture, home decor, and educational/scientific collecting.
Geological facts
Petrified wood is the official state fossil of Arizona. The organic cellular structure is often preserved so perfectly that tree rings and bark patterns can be studied under a microscope.
Field identification & locations
Identify by looking for distinct wood grain patterns or bark-like textures in a heavy, cold-to-the-touch stony material. Common in areas like the Petrified Forest National Park (Arizona), Madagascar, and Indonesia.
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