fossil

Petrified Wood

Silicified wood (SiO2)

Hardness: 6.5-7 (Mohs); Color: Red, brown, yellow, black; Luster: Vitreous to waxy; Structure: Cryptocrystalline quartz preserving original organic cellular structure.

Hardness: 6
Color: Red, brown, yellow, black
Luster: Vitreous to waxy

Identified July 17, 2026More fossil →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Red, brown, yellow, black; Luster: Vitreous to waxy; Structure: Cryptocrystalline quartz preserving original organic cellular structure.

Formation & geological history

Formed through permineralization where organic wood materials are replaced by minerals, typically silica from volcanic ash, in anaerobic environments over millions of years (often Triassic to Eocene).

Uses & applications

Ornamental display, jewelry (cabochons), furniture (table tops), and geological study.

Geological facts

The Petrified Forest National Park in Arizona contains some of the world's most famous specimens, dating back over 200 million years to the Late Triassic.

Field identification & locations

Identify by looking for bark textures and growth rings in heavy, stony material. Found in sedimentary beds with high volcanic ash content; common in the American Southwest, Madagascar, and Indonesia.