mineral

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, cream; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.6-2.9

Hardness: 6
Color: Brown, tan, cream
Luster: Vitreous to dull

Identified May 25, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, cream; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: 2.6-2.9

Formation & geological history

Formed when plant material is buried by sediment and protected from decay by oxygen and organisms. Graded minerals from groundwater, typically silica, replace the organic matter cell by cell. Most specimens range from late Paleozoic to various Cenozoic eras.

Uses & applications

Used primarily for jewelry (cabochons), interior decoration (tables, bookends), and as highly sought-after collector pieces.

Geological facts

Arizona's Petrified Forest National Park contains one of the world's largest concentrations of petrified wood. It is the state fossil of Arizona and Louisiana.

Field identification & locations

Identify in the field by looking for bark textures or concentric growth rings in a stone that is much harder than typical sedimentary rock. Common in sedimentary basins after erosion.