fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5 to 7 on the Mohs scale. Color: Brown, tan, reddish-brown, and gray with distinct fibrous wood grain textures. Luster: Vitreous to waxy. Cleavage: None (conchoidal fracture). Specific Gravity: ~2.6-2.65.

Hardness: 6
Luster: Vitreous to waxy

Identified July 25, 2026More fossil →

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Physical properties

Formation & geological history

Formed via permineralization, where organic wood material buried under sediment or volcanic ash is replaced by dissolved minerals (predominantly silica/chalcedony) over millions of years while retaining the original cellular structures of the tree.

Uses & applications

Used for decorative lapidary work, jewelry, stone carvings, bookends, and display specimens for fossil collectors.

Geological facts

The process of petrifaction turns ancient trees into solid quartz minerals. The Petrified Forest National Park in Arizona is one of the world's most famous locations for petrified wood, dating back to the Triassic Period (approx. 225 million years ago).

Field identification & locations

Identified in the field by its distinct parallel fibrous growth rings or bark texture combined with the weight, coldness, and hardness of quartz/agate. Commonly found in riverbeds, desert wash areas, and sedimentary rock deposits.