fossil

Polished petrified wood

Silicified wood; primarily microcrystalline quartz (SiO₂) replacing woody tissue

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; tan, cream, brown, and gray colors with preserved wood-like patterns; waxy to vitreous luster; cryptocrystalline quartz, with no prominent cleavage; specific gravity about 2.5–2.7.

Identified September 21, 2026More fossil →

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Physical properties

Formation & geological history

A fossilized tree fragment formed when silica-rich groundwater gradually replaced organic wood, commonly during the Cenozoic or earlier. The specimen appears cut and polished, with weathered outer rind and lighter silicified interior.

Uses & applications

Used as a decorative stone, paperweight, cabochon, and lapidary material; attractive patterned pieces may be collectible.

Geological facts

Silicification can preserve cellular structure in remarkable detail, sometimes visible under magnification. Color commonly comes from iron, manganese, carbon, or other trace impurities.

Field identification & locations

Identify by recognizable growth-ring or fibrous wood texture, hardness, density, and lack of organic softness; common deposits occur in volcanic ash-bearing sediments worldwide, including Arizona, Indonesia, Madagascar, and Australia.