fossil

Polished petrified wood

Silicified wood; commonly quartz/chalcedony (SiO₂) replacing wood tissue

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; dark gray to black polished interior with brown, tan, and cream weathered rind. Waxy to vitreous luster, cryptocrystalline quartz structure, and no prominent cleavage; density typically 2.4–2.7 g/cm³.

Identified September 18, 2026More fossil →

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Physical properties

Formation & geological history

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

Uses & applications

Used as ornamental stone, bookends, cabochons, polished slices, and collectible fossil material; not generally used structurally.

Geological facts

The dark interior may reflect carbon-rich wood, manganese/iron staining, or dense chalcedony. Fine specimens preserve annual rings, bark, and cellular detail despite complete replacement by minerals.

Field identification & locations

Identify it by visible wood grain or rings, very high hardness, silica-like polish, and a natural bark-like outer rind; it should not be soft or splinter like wood. Common sources include Arizona, Indonesia, Madagascar, Australia, and Argentina.