fossil

Fossilized wood (petrified wood)

Silicified permineralized wood, commonly quartz (SiO₂) replacing or infilling woody tissue

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, with tan, brown, gray, or reddish colors, waxy to glassy luster, and preserved fibrous or growth-ring texture. It lacks prominent cleavage and commonly has specific gravity around 2.5–2.7.

Identified September 5, 2026More fossil →

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Physical properties

Formation & geological history

Buried wood was gradually permineralized as silica-rich groundwater filled pores and replaced organic tissues, often during volcanic or fluvial burial. Ages range from millions to hundreds of millions of years; the pictured specimen appears weathered and partially silicified.

Uses & applications

Used as a collectible, lapidary material, cabochons, polished slices, bookends, and decorative objects; it is generally not used as structural stone.

Geological facts

The cellular anatomy and grain can remain recognizable despite complete mineral replacement. Some specimens preserve bark, annual rings, knots, or even microscopic vascular structures.

Field identification & locations

Identify it by visible wood grain, bark-like texture, very high hardness, and resistance to scratching by a steel knife; a streak or acid test is less diagnostic. Common localities include Arizona, Indonesia, Madagascar, Australia, and Argentina.