fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness of 6.5 to 7 on the Mohs scale, predominantly brown, tan, and grey with distinct wood grain patterns, vitreous to waxy luster, amorphous crystal structure (microcrystalline quartz), no true cleavage, specific gravity of 2.5 to 2.8.

Identified August 4, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization when buried tree logs are covered by sediment in an oxygen-poor environment, where groundwater rich in dissolved silica replaces the organic cellular structure with stone over millions of years.

Uses & applications

Used in decorative items, jewelry, bookends, lapidary art, and highly valued as a collector's specimen.

Geological facts

The petrification process can preserve microscopic cellular details of ancient plants that lived millions of years ago, sometimes dating back to the Triassic period over 200 million years ago.

Field identification & locations

Easily identified by retaining the external or internal texture and growth rings of wood combined with the heavy weight and hardness of stone. Found worldwide, with notable deposits in Arizona, USA and Madagascar.