fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness of 7 on the Mohs scale; colors range from brown, red, and yellow to gray and black depending on trace minerals like iron or manganese; vitreous to waxy luster; amorphous microcrystalline quartz (chalcedony/jasper) crystal structure; no cleavage; specific gravity around 2.5 - 2.7.

Identified August 2, 2026More fossil →

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Physical properties

Formation & geological history

Formed when organic plant material is buried in an oxygen-deficient, sediment-rich environment and groundwater rich in dissolved silica slowly replaces the original cellular structure with quartz over millions of years.

Uses & applications

Used for ornamental carvings, polished display specimens, jewelry, tabletops, and highly prized by fossil and mineral collectors.

Geological facts

The petrification process preserves microscopic cellular details of the original ancient trees, allowing scientists to study ancient ecosystems dating back hundreds of millions of years.

Field identification & locations

Identified by retaining the exterior shape, growth rings, or wood grain texture of wood while possessing the extreme hardness, weight, and cold feel of solid stone. Found worldwide, famously at the Petrified Forest National Park in Arizona.