sedimentary

Petrified Wood

Silicified Wood (primarily SiO₂)

Hardness: 6.5-7 on Mohs scale. Color: Tan, grey, brown, or reddish. Luster: Dull to waxy or vitreous. Structure: Microcrystalline quartz (chalcedony/opal) preserving organic cellular structures. Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Tan, grey, brown, or reddish
Luster: Dull to waxy or vitreous

Identified June 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through permineralization where organic wood is replaced by minerals, typically silica, in anaerobic conditions. This specimen from Freestone County, TX, likely dates to the Eocene or Paleocene (~35-60 million years ago) within the Wilcox or Claiborne groups.

Uses & applications

Highly valued as a lapidary material for jewelry, bookends, and decorative ornaments. Large specimens are used in landscaping and as museum-quality display pieces.

Geological facts

The Texas State Stone is petrified palm wood, which is closely related to this specimen. These fossils form when trees are buried by sediment or volcanic ash, protecting them from decay while mineral-rich groundwater replicates the wood grain in stone.

Field identification & locations

Identify by looking for characteristic bark textures, growth rings, or knots in what otherwise feels like heavy, cold stone. Common in the Gulf Coastal Plain of Texas. Collectors should look for high-definition cell structure.