fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Shades of brown, yellow, red, orange, green, and gray; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline (trigonal); Cleavage: None, exhibits conchoidal fracture

Hardness: 6
Color: Shades of brown, yellow, red, orange, green, and gray
Luster: Waxy to vitreous

Identified July 23, 2026More fossil →

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Physical properties

Formation & geological history

Formed when plant material is buried by sediment and protected from decay due to oxygen deficiency. Mineral-rich groundwater flowing through the sediment deposits minerals in the plant's cells, replacing organic matter over millions of years (Permineralization).

Uses & applications

Used for making ornamental objects, lapidary carvings, bookends, jewelry (cabochons), and as display specimens for fossil collectors.

Geological facts

The process of petrifaction preserves organic structures down to the microscopic cell wall detail. Colors are caused by trace elements like iron oxide (reds/yellows), copper/chromium (greens/blues), and manganese (pinks/purples).

Field identification & locations

Identified by distinct tree ring patterns, bark textures, and woody fiber structures combined with the weight and hardness of stone. Commonly found in Arizona (Petrified Forest National Park), Oregon, Madagascar, and Indonesia.