sedimentary

Petrified Wood

Silicified Wood (primarily Chalcedony or Quartz, SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, reddish, and gray; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None; Specific Gravity: 2.6-2.9.

Hardness: 6
Color: Brown, tan, reddish, and gray
Luster: Waxy to vitreous

Identified May 10, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, reddish, and gray; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None; Specific Gravity: 2.6-2.9.

Formation & geological history

Formed through permineralization where organic wood materials are replaced by silica-rich minerals (often from volcanic ash) over millions of years. Common in Triassic to Tertiary deposits.

Uses & applications

Used for ornamental furniture, high-end interior design slabs, lapidary art, jewelry, and as a popular collector's specimen.

Geological facts

Famous locations include the Petrified Forest National Park in Arizona. It is a 'body fossil' where the original cellular structure is often preserved in stone.

Field identification & locations

Identified by its wood-like texture and growth rings preserved in a hard, stony material. Commonly found in sedimentary basins and areas with historical volcanic activity.