sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
Hardness: 6.5–7 on Mohs scale; Color: Brown, tan, reddish-brown; Luster: Dull to waxy; Crystal structure: Amorphous or microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6–2.9
- Hardness
- 6
- Color
- Brown, tan, reddish-brown
- Luster
- Dull to waxy
Identified More sedimentary →
Explore Petrified Wood in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Brown, tan, reddish-brown; Luster: Dull to waxy; Crystal structure: Amorphous or microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6–2.9
Formation & geological history
Formed through permineralization where organic wood material is replaced by minerals, typically silica, over millions of years in an anaerobic environment like volcanic ash or river sediments.
Uses & applications
Used for ornamental carvings, jewelry (cabochons), furniture (slices for tabletops), and as decorative museum or collector specimens.
Geological facts
Petrified wood is the state fossil of Arizona. The process preserves the cellular structure of the original tree so well that tree rings and bark patterns are often visible.
Field identification & locations
Identify by looking for wood-like grain, bark textures, and growth rings on a stone that is much heavier and harder than actual wood. Common in the Petrified Forest National Park (Arizona) and similar desert or volcanic regions.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary