fossil

Petrified wood

Silicified fossil wood, primarily quartz (SiO₂) replacing cellulose

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown to tan with cream wood-grain banding, dull to waxy luster, microcrystalline quartz structure, no obvious cleavage, and specific gravity around 2.5–2.7.

Identified September 8, 2026More fossil →

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Physical properties

Hardness about 6.5–7 Mohs; brown to tan with cream wood-grain banding, dull to waxy luster, microcrystalline quartz structure, no obvious cleavage, and specific gravity around 2.5–2.7.

Formation & geological history

Buried wood was preserved and gradually replaced by silica-rich groundwater, often during volcanic or sedimentary burial; specimens range from Paleozoic to Cenozoic in age, commonly tens of millions of years old.

Uses & applications

Used as a decorative stone, paperweight, cabochon, polished slab, and lapidary material; attractive pieces are collected rather than used structurally.

Geological facts

The visible grain and growth-ring-like patterns are cellular wood anatomy mineralized by chalcedony or quartz. Color variations may reflect iron, manganese, carbon, or other trace impurities.

Field identification & locations

Identify it by recognizable wood grain, very high hardness, heaviness, and lack of organic softness; it commonly occurs in volcanic ash beds, river gravels, and arid regions such as Arizona, Indonesia, Madagascar, and Argentina.