fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: tan, brown, beige, and cream with translucent quartz layers. Luster: vitreous (glassy) to waxy. Structure: preserves the original cellular structure of wood. Specific gravity: 2.6-2.9.

Hardness: 6
Color: tan, brown, beige, and cream with translucent quartz layers
Luster: vitreous (glassy) to waxy

Identified July 2, 2026More fossil →

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Physical properties

Formation & geological history

Formed via permineralization where organic wood material is replaced by silica-rich minerals (quartz or chalcedony) while buried under sediment or volcanic ash. This typically occurs over millions of years, often dating back to the Triassic or Cenozoic eras.

Uses & applications

Used for decorative items, jewelry (cabochons), bookends, and educational fossil collecting. Polished slabs are highly valued in interior design.

Geological facts

The Petrified Forest National Park in Arizona contains one of the world's largest concentrations of petrified wood. It is essentially a 'stone tree' where the wood was replaced by minerals so perfectly that tree rings are often visible.

Field identification & locations

Identify by looking for wood-like grain patterns or bark-like textures on a heavy, stone specimen. Common in arid environments or areas with history of volcanic activity. Unlike real wood, it will not scratch with a knife and feels very cold to the touch.