metamorphic
Petrified Wood
Silicified wood (primarily SiO2)
Hardness: 6.5-7 (Mohs); Color: Brown, tan, cream with visible grain patterns; Luster: Vitreous to waxy; Structure: Microcrystalline quartz (Chalcedony/Jasper); Specific Gravity: 2.6-2.9
- Hardness
- 6
- Color
- Brown, tan, cream with visible grain patterns
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Brown, tan, cream with visible grain patterns; Luster: Vitreous to waxy; Structure: Microcrystalline quartz (Chalcedony/Jasper); Specific Gravity: 2.6-2.9
Formation & geological history
Formed through permineralization where organic plant matter is replaced by minerals, typically silica, under anaerobic conditions in volcanic ash or sedimentary basins over millions of years.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), interior decoration (tabletops, bookends), and as a popular geological collectible.
Geological facts
Petrified wood is the state fossil of Washington and Arizona. Famous sites like the Petrified Forest National Park in Arizona contain logs that are over 200 million years old from the Triassic period.
Field identification & locations
Identify in the field by looking for distinct tree ring patterns, bark textures, or knots preserved in stone. Found globally in ancient riverbeds and volcanic regions. Collectors look for high color contrast and preservation of cellular structure.
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