fossil

Petrified Wood

Silicified Wood (primarily Chalcedony/Quartz, SiO2)

Hardness: 6.5–7 on Mohs scale. Color: Brown, tan, gray, and black. Luster: Waxy to vitreous. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None. Specific Gravity: 2.6–2.9.

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

Identified July 19, 2026More fossil →

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Physical properties

Hardness: 6.5–7 on Mohs scale. Color: Brown, tan, gray, and black. Luster: Waxy to vitreous. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None. Specific Gravity: 2.6–2.9.

Formation & geological history

Formed through permineralization, a process where organic wood cells are replaced by minerals (usually silica) from groundwater over millions of years. Most common in sedimentary environments like river beds or volcanic ash deposits.

Uses & applications

Used for ornamental purposes, jewelry (cabochons), interior decor (tabletops), and as a highly collectible paleontological specimen.

Geological facts

Petrified wood retains the original cellular structure of the wood, allowing scientists to identify the specific tree species that lived millions of years ago. Some of the most famous deposits are in the Petrified Forest National Park in Arizona.

Field identification & locations

Identify by looking for wood-like grain patterns, tree rings, or bark textures on a cold, heavy, stone-like material. It will not burn and is much harder than natural wood. Commonly found in areas with ancient volcanic activity and sedimentary basins.

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