fossil

Petrified Wood

Silicified Wood (primarily SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Brown, black, reddish-orange from iron oxides. Luster: Dull to waxy. Structure: Preserves original cellular plant structure through permineralization.

Hardness: 6
Color: Brown, black, reddish-orange from iron oxides
Luster: Dull to waxy

Identified July 17, 2026More fossil →

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Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Brown, black, reddish-orange from iron oxides. Luster: Dull to waxy. Structure: Preserves original cellular plant structure through permineralization.

Formation & geological history

Formed when ancient trees were buried by sediment or volcanic ash, excluding oxygen and allowing mineral-rich groundwater to replace organic matter with silica over millions of years (often Mesozoic or Cenozoic).

Uses & applications

Used for lapidary work, jewelry, interior decor (bookends, tabletops), and as geological teaching specimens.

Geological facts

The process can preserve details as small as tree rings and individual cells. Some of the most famous deposits are in the Petrified Forest National Park in Arizona, dating back to the Triassic period.

Field identification & locations

Identify by looking for bark textures, wood grain, or growth rings in a heavy, stone-like material. Often found in badlands or areas with historical volcanic activity. Harder than steel; it will scratch a knife blade.