sedimentary

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Red, brown, tan, and orange due to iron oxides; Luster: Vitreous to waxy; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9

Hardness: 6
Color: Red, brown, tan, and orange due to iron oxides
Luster: Vitreous to waxy

Identified May 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through permineralization where organic wood materials are replaced by silicate minerals under anaerobic conditions, typically in ash-rich sedimentary environments. Ages range from Devonian to Pleistocene.

Uses & applications

Used for decorative objects, lapidary arts, jewelry, high-end furniture (slabs), and as geological collector specimens.

Geological facts

In petrified wood, the original cellular structure of the plant is often preserved in incredible detail, even though no organic material remains. The colors are determined by trace elements like iron (red/yellow), manganese (pink/orange), and carbon (black).

Field identification & locations

Identify by looking for wood-like grain, bark patterns, or growth rings combined with a stone-like hardness and weight. Commonly found globally in areas like Arizona (USA), Madagascar, and Indonesia.

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