fossil

Petrified wood

Silicified fossil wood; commonly quartz (SiO₂) replacing wood

AI-generated identification · may be incorrect

Typically hardness ~6.5–7 Mohs, brown to reddish-brown color, waxy to vitreous luster, and preserved wood grain; it has no true cleavage and is often dense and heavy. The pictured piece appears naturally weathered, possibly partly polished or coated, though visual identification is not definitive.

Identified August 10, 2026More fossil →

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Physical properties

Formation & geological history

Groundwater carrying dissolved silica gradually replaces cellular wood while preserving its structure, usually during burial in volcanic-ash-rich sediments. Ages commonly range from millions to hundreds of millions of years, depending on the deposit.

Uses & applications

Used for lapidary slabs, cabochons, carvings, bookends, and ornamental specimens; attractive patterned pieces are collectible.

Geological facts

Silica replacement can preserve growth rings, vessels, and even microscopic cellular detail. Iron and manganese impurities commonly produce the red, brown, and black coloration.

Field identification & locations

Identify it by recognizable wood grain, ring structure, mineral-like weight, and a hardness that can scratch glass; unlike ordinary wood, it does not burn or absorb water readily. Common localities include Arizona, Madagascar, Indonesia, Australia, and Argentina.