fossil

Petrified Wood

Silicified wood (principally SiO2)

Hardness: 6.5-7 (Mohs scale), Color: tan, grey, brown, and black streaks, Luster: dull to waxy/vitreous, Crystal structure: cryptocrystalline (chalcedony/quartz), Specific gravity: 2.6-2.9

Hardness: 6

Identified July 16, 2026More fossil →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: tan, grey, brown, and black streaks, Luster: dull to waxy/vitreous, Crystal structure: cryptocrystalline (chalcedony/quartz), Specific gravity: 2.6-2.9

Formation & geological history

Formed through permineralization where organic wood materials are replaced by minerals (usually silica) while retaining original anatomical structure. Typically dates from the Carboniferous to the Holocene.

Uses & applications

Used for ornamental carvings, jewelry (cabochons), furniture tops, and as a popular educational or decorative collector\'s specimen.

Geological facts

Petrified wood can preserve microscopic details such as tree rings and cellular structure. The colors are caused by trace elements like iron (red/yellow), manganese (pink/orange), or carbon (black).

Field identification & locations

Look for distinctive rings, bark texture, or wood grain patterns preserved in a heavy, stone-like material. Common in areas with ancient volcanic activity and sedimentary basins like Arizona\'s Petrified Forest.