fossil

Petrified Wood

Silicified Wood (primarily SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Brown, tan, reddish, grey, black; Luster: Dull to vitreous/waxy; Structure: Retains original organic plant structure (growth rings, bark texture, cellular detail); Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Brown, tan, reddish, grey, black
Luster: Dull to vitreous/waxy

Identified July 26, 2026More fossil →

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Physical properties

Formation & geological history

Formed when plant material is buried by sediment and protected from decay due to a lack of oxygen. Mineral-rich groundwater flowing through the sediment deposits silica (quartz, chalcedony, or opal) into the plant cells, replacing organic matter over millions of years.

Uses & applications

Used for lapidary work, decorative display pieces, bookends, jewelry, furniture (tabletops), and educational geological collections.

Geological facts

Some petrified wood specimens preserve detailed cellular structures including individual tree rings and bark texture. The vivid colors are often caused by trace elements: iron yields red/brown/yellow tones, manganese causes pink/orange, and copper or chromium causes green/blue shades.

Field identification & locations

Identify in the field by looking for distinct wood grain, growth rings, and bark textures on a material that has the hardness, weight, and cool feel of stone or quartz. Commonly found in riverbeds, badlands, and sedimentary deposits.