metamorphic
Petrified Wood
Silicified wood (primarily Quartz/Chalcedony, SiO2)
Hardness: 6.5-7 (Mohs); Color: Tan, brown, reddish-brown with visible grain; Luster: Waxy to vitreous; Crystal structure: Microcrystalline (cryptocrystalline); Specific gravity: 2.6-2.9
- Hardness
- 6
- Color
- Tan, brown, reddish-brown with visible grain
- Luster
- Waxy to vitreous
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs); Color: Tan, brown, reddish-brown with visible grain; Luster: Waxy to vitreous; Crystal structure: Microcrystalline (cryptocrystalline); Specific gravity: 2.6-2.9
Formation & geological history
Formed through permineralization where organic wood materials are replaced by minerals (silica) over millions of years, typically in volcanic ash or sedimentary river deposits; ages range from Devonian to Pleistocene.
Uses & applications
Used for jewelry (cabochons), lapidary art, decorative bookends, furniture tops, and as a popular teaching and collecting specimen.
Geological facts
Arizona's Petrified Forest National Park contains one of the world's largest and most colorful concentrations of petrified wood. It is the state fossil of Arizona and the state stone of Washington.
Field identification & locations
Identify in the field by looking for distinct wood grain patterns, growth rings, or bark textures in a stone that is heavy and cannot be scratched by a steel knife. Common in sedimentary basins with a history of volcanic activity.
More like this
