fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness of 7 on the Mohs scale, colors ranging from white, gray, and brown to reds and yellows, vitreous to waxy luster, amorphous crystal structure (quartz pseudomorph), no true cleavage, specific gravity of 2.5-2.7.

Identified August 4, 2026More fossil →

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Physical properties

Formation & geological history

Formed when fallen trees are rapidly buried in sediment low in oxygen, preventing decay. Over millions of years, groundwater rich in dissolved silica replaces the organic wood cell walls with stone.

Uses & applications

Used for ornamental carvings, polished display specimens, jewelry, and lapidary art.

Geological facts

Petrified wood can preserve the microscopic cellular structure of the original tree down to the ring patterns, making it a valuable tool for paleobotanists.

Field identification & locations

Can be identified in the field by its distinct wood-like grain and texture combined with a stone-like weight and coldness. Found globally, notably in places like the Petrified Forest National Park in Arizona.