fossil

Petrified wood

Silicified fossil wood, commonly quartz/chalcedony (SiO₂) replacing woody tissue

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, reddish-brown, and gray coloration with subdued vitreous to waxy luster. It preserves fibrous wood grain, with no prominent cleavage; density is typically 2.3–2.7 g/cm³.

Identified September 10, 2026More fossil →

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Physical properties

Formation & geological history

Buried wood was mineralized as silica-rich groundwater replaced the organic structure, usually during the Cenozoic or Mesozoic; exact age requires locality information. The specimen appears naturally weathered and fragmentary.

Uses & applications

Used as a decorative stone, cabochon material, bookends, carvings, and educational or fossil specimens; lapidary value depends on pattern, color, polishability, and completeness.

Geological facts

The original cellular wood anatomy can remain visible at microscopic scale despite complete replacement by quartz or chalcedony. Iron oxides commonly produce its red and brown colors.

Field identification & locations

Identify it by recognizable grain or growth structure, very high hardness, silica-like fracture, and lack of lightweight organic texture; common sources include Arizona, Utah, Indonesia, Madagascar, and Australia. A small rough fragment is commonly worth about $5–$30, while unusual, highly patterned, or large specimens may bring $50–$300+.