sedimentary

Petrified Wood

Silicified Wood (primarily SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Brown, tan, reddish-brown. Luster: Dull to waxy. Crystal structure: Cryptocrystalline (chalcedony/quartz). Cleavage: None. Specific Gravity: 2.6-2.9.

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

Identified May 20, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Brown, tan, reddish-brown. Luster: Dull to waxy. Crystal structure: Cryptocrystalline (chalcedony/quartz). Cleavage: None. Specific Gravity: 2.6-2.9.

Formation & geological history

Formed through permineralization where organic plant material is replaced by minerals, typically silica from volcanic ash, over millions of years. Most common in Mesozoic formations.

Uses & applications

Used for carvings, bookends, lapidary work, jewelry (cabochons), and as museum or private collection display specimens.

Geological facts

Unlike most fossils, petrified wood is a three-dimensional representation of the original organic material, often preserving microscopic cellular details of the original tree bark and rings.

Field identification & locations

Identify by looking for bark-like textures, growth rings, and a hardness that prevents scratching by a steel blade. Commonly found in areas with ancient volcanic activity and sedimentary basins.