fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 Mohs; Color: Brown, tan, reddish; Luster: Vitreous to waxy; Structure: Cryptocrystalline (replacing original wood grain); SG: 2.6-2.9

Hardness: 6
Color: Brown, tan, reddish
Luster: Vitreous to waxy

Identified July 9, 2026More fossil →

Explore Petrified Wood in the encyclopedia →

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; Color: Brown, tan, reddish; Luster: Vitreous to waxy; Structure: Cryptocrystalline (replacing original wood grain); SG: 2.6-2.9

Formation & geological history

Formed when plant material is buried by sediment and protected from decay. Groundwater rich in dissolved solids (silica) flows through the sediment, replacing original plant material with minerals over millions of years (Permian to Pleistocene).

Uses & applications

Used for jewelry, lapidary arts, decorative furniture (slabs), and as a popular collector's specimen.

Geological facts

Depending on the minerals present during fossilization, petrified wood can show a rainbow of colors; iron oxides produce reds and yellows, while manganese produce pinks and oranges.

Field identification & locations

Identify by looking for preserved growth rings, bark textures, or wood grain patterns that have been turned into stone. Common in places like Arizona (USA), Madagascar, and Indonesia.