fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 on the Mohs scale, Color: Brown, tan, white, and black with wood grain patterns, Luster: Vitreous to waxy, Crystal Structure: Microcrystalline quartz (chalcedony/jasper), Cleavage: None (conchoidal fracture), Specific Gravity: 2.5-2.7

Hardness: 6

Identified August 6, 2026More fossil →

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Physical properties

Formation & geological history

Formed when fallen trees are rapidly buried in low-oxygen, mineral-rich sediment like volcanic ash or flood plains, allowing groundwater rich in dissolved silica to slowly replace the organic cellular structure with quartz over millions of years.

Uses & applications

Used in lapidary arts, making decorative slabs, bookends, jewelry, and prized by fossil and mineral collectors.

Geological facts

The process of permineralization can preserve the most minute cellular details of the original tree, allowing scientists to identify ancient species that lived tens of millions of years ago.

Field identification & locations

Identified by retaining the distinct texture, growth rings, and fibrous look of real wood while feeling heavy like stone and scratching glass. Commonly found in regions with ancient volcanic activity or flood deposits, such as the Petrified Forest in Arizona.