fossil

Petrified Wood

Silicified Wood (Silicon Dioxide - SiO2)

Hardness: 6.5 - 7 on Mohs scale; Color: Brown, reddish-brown, tan, and gray; Luster: Dull to waxy; Structure: Microcrystalline (retains original cellular wood structure); Specific Gravity: 2.6 - 2.8

Hardness: 6
Color: Brown, reddish-brown, tan, and gray
Luster: Dull to waxy

Identified July 26, 2026More fossil →

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Physical properties

Hardness: 6.5 - 7 on Mohs scale; Color: Brown, reddish-brown, tan, and gray; Luster: Dull to waxy; Structure: Microcrystalline (retains original cellular wood structure); Specific Gravity: 2.6 - 2.8

Formation & geological history

Formed when plant material is buried by sediment and lack of oxygen inhibits aerobic decomposition. Groundwater rich in dissolved minerals (mainly silica) flows through the sediment, replacing original organic materials with minerals.

Uses & applications

Used in lapidary work, jewelry, decorative carvings, bookends, educational displays, and rock collections.

Geological facts

Petrified wood preserves original cellular tree details down to the microscopic level. Famous locations like the Petrified Forest National Park in Arizona feature trees that lived over 200 million years ago during the Late Triassic period.

Field identification & locations

Identified in the field by its distinctive wood-grain texture and tree rings combined with the hardness and density of stone or agate. Commonly found in sedimentary basins worldwide, particularly in Arizona, Oregon, Utah, and Madagascar.

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