sedimentary

Petrified Wood

Silicified Wood (primarily SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Tan, beige, or grey with wood-like texture; Luster: Dull to waxy; Crystal Structure: Cryptocrystalline (Microcrystalline Quartz); Specific Gravity: 2.6-2.9

Hardness: 6
Color: Tan, beige, or grey with wood-like texture
Luster: Dull to waxy

Identified May 24, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Tan, beige, or grey with wood-like texture; Luster: Dull to waxy; Crystal Structure: Cryptocrystalline (Microcrystalline Quartz); Specific Gravity: 2.6-2.9

Formation & geological history

Formed via permineralization where organic wood materials are replaced by minerals (usually silica) in anaerobic sedimentary environments, typically dating from the Devonian to the Holocene periods.

Uses & applications

Used in ornamental jewelry (cabochons), interior design (furniture, bookends), and as educational or geological collectibles.

Geological facts

The process of petrifaction happens deep underground when wood becomes buried under sediment or volcanic ash. Water rich in dissolved solids flows through the sediment, replacing the plant cells with stone while preserving original structure.

Field identification & locations

Identify by looking for cylindrical shapes, bark-like exterior textures, and internal rings. Commonly found in Arizona (USA), Argentina, and Egypt. Collectors look for cell-level preservation.