mineral

Petrified Wood

Silicified Wood / Chalcedony (SiO2)

Hardness: 6.5-7.0 on Mohs scale. Color: Brownish-yellow, tan, and earthy tones due to iron oxides. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.9.

Hardness: 6
Color: Brownish-yellow, tan, and earthy tones due to iron oxides
Luster: Waxy to vitreous

Identified April 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the process of permineralization, where organic wood material is replaced by minerals, typically silica, from groundwater after being buried by sediment or volcanic ash. This specimen likely dates from the Paleozoic to Cenozoic eras.

Uses & applications

Primarily used for lapidary work, jewelry (cabochons), interior decor, and as educational geological specimens for collectors.

Geological facts

Petrified wood is the state fossil of Arizona. The process of petrifaction happens in excluding oxygen, which prevents the wood from decaying naturally while minerals seep into the cell structures.

Field identification & locations

Identify in the field by looking for 'wood-grain' textures, ring structures, or bark-like patterns in a stone that is too hard to be scratched by a steel knife. Commonly found in riverbeds or volcanic regions like the American Southwest.