mineral

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 Mohs; Color: Brown, red, amber, and black; Luster: Vitreous to waxy; Structure: Cryptocrystalline quartz; Cleavage: None; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Brown, red, amber, and black
Luster: Vitreous to waxy

Identified March 3, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, red, amber, and black; Luster: Vitreous to waxy; Structure: Cryptocrystalline quartz; Cleavage: None; Specific Gravity: 2.6-2.9

Formation & geological history

Formed through permineralization when organic plant matter is buried under sediment or volcanic ash and replaced by silica-rich water over millions of years (typically Mesozoic or Cenozoic).

Uses & applications

Used for jewelry (cabochons), interior design (tables, bookends), fossil collecting, and historical geological studies.

Geological facts

The colors in petrified wood are caused by trace elements; for example, iron creates reds and yellows, while manganese creates pinks and blacks. Arizona's Petrified Forest National Park contains one of the largest concentrations in the world.

Field identification & locations

Identify in the field by looking for bark textures, growth rings, and wood-like structures preserved in a heavy, glassy rock. Found worldwide in areas of ancient forests or volcanic activity.