mineral

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Hardness: 6.5–7 on Mohs scale; Color: Brown, tan, cream, and grey; Luster: Vitreous to waxy; Crystal structure: Cryptocrystalline (microscopic quartz/chalcedony); Cleavage: None (conchoidal fracture); Specific gravity: 2.6–2.9.

Hardness: 6
Color: Brown, tan, cream, and grey
Luster: Vitreous to waxy

Identified March 14, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed through permineralization where organic wood is gradually replaced by silica (quartz) from groundwater while buried under sediment or volcanic ash. This specimen likely dates from the Triassic to the Neogene period (200 million to 2 million years ago).

Uses & applications

Used in jewelry (cabochons), interior design (polished bookends, tables), and popular as educational and aesthetic fossils for collectors.

Geological facts

In some specimens, the replacement is so precise that microscopic structures like tree rings and individual plant cells remain visible. The largest concentration of these specimens is in the Petrified Forest National Park in Arizona.

Field identification & locations

Identify in the field by looking for bark-like external textures combined with a heavy, rock-like weight and glassy internal fracture appearance. Common in areas with ancient sedimentary basins or volcanic deposits like Arizona, Oregon, and Madagascar.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral