fossil

Polished petrified wood

Silicified wood; predominantly microcrystalline quartz (SiO₂), often chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; polished glassy to waxy luster, brown, burgundy, cream, and golden colors, with visible fibrous wood grain and replacement textures. It is typically massive rather than crystalline and has no obvious cleavage; specific gravity is about 2.5–2.7.

Identified August 24, 2026More fossil →

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Physical properties

Formation & geological history

Buried wood was gradually replaced by silica-rich groundwater during diagenesis, preserving cellular and growth-ring structures. Most examples formed during the Cenozoic or Mesozoic, though age depends on locality.

Uses & applications

Used as a polished decorative slab, sculpture, paperweight, and collector specimen; occasionally used in jewelry and ornamental stonework.

Geological facts

The wood’s organic material is replaced molecule by molecule by quartz or chalcedony, producing a fossil while retaining its original anatomy. Red and brown colors commonly reflect iron oxides, while pale areas may contain calcite or other minerals.

Field identification & locations

Identify it by recognizable wood grain, annual rings, cellular patterns, very high hardness, and inability to scratch with a steel knife easily. Common sources include Arizona, Indonesia, Madagascar, Brazil, and Australia.