sedimentary

Petrified Wood

Silicified wood (Quartz/Chalcedony replacement of cellulose)

AI-generated identification · may be incorrect

Hardness: 6.5-7.0 (Mohs scale); Color: Variegated brown, tan, white, and gray; Luster: Vitreous to waxy; Crystal structure: Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Variegated brown, tan, white, and gray
Luster: Vitreous to waxy

Identified May 24, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7.0 (Mohs scale); Color: Variegated brown, tan, white, and gray; Luster: Vitreous to waxy; Crystal structure: Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.9

Formation & geological history

Formed through permineralization where organic wood materials are replaced by minerals (usually silica) while retaining the original structure. Commonly dates from the Triassic to the Tertiary periods.

Uses & applications

Used primarily for decorative objects, jewelry (cabochons), collection specimens, and interior design accents such as bookends and tabletops.

Geological facts

The Arizona Petrified Forest is the most famous location; the process occurs in the absence of oxygen to prevent rotting before minerals can saturate the wood cells.

Field identification & locations

Look for visible tree ring patterns or bark-like textures that are stone-hard. Found globally in ancient riverbeds and volcanic ash deposits. Collectors value pieces with clear cellular preservation.