metamorphic

Petrified Wood

Silicified Wood (primarily Quartz / Chalcedony: SiO2)

AI-generated identification · may be incorrect

Hardness: 7.0 on Mohs scale; Color: Variable (reds, tans, browns, blacks, grays); Luster: Vitreous to waxy; Structure: Pseudomorphous (internal wood grain, rings, and bark textures preserved by silica); Opaque to translucent; Specific Gravity: 2.6–2.9.

Hardness: 7
Color: Variable (reds, tans, browns, blacks, grays)
Luster: Vitreous to waxy

Identified March 22, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed through permineralization over millions of years (typically 20-300 million years old). Organic material is replaced by minerals like silica, calcite, or pyrite while buried under sediment/volcanic ash, depriving it of oxygen and preventing rot.

Uses & applications

Used for ornamental furniture (tabletops), lapidary work (jewelry, cabochons, bookends), landscaping, and as a highly sought-after specimen for geological collectors.

Geological facts

The largest concentration is in Petrified Forest National Park, Arizona. It provides a unique biological record of extinct flora. Each color represents a trace element: iron causes reds/oranges, manganese creates purples/blacks, and copper/cobalt create blues/greens.

Field identification & locations

Identify in the field by looking for rock-hard specimens with distinct bark textures, growth rings, or wood-like fractures and grain. Commonly found in sedimentary basins or areas with historical volcanic activity. Note: Collecting on US federal lands is strictly regulated or illegal.