mineral

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 Mohs; Color: Tan, brown, white, and grey with wood-grain patterns; Luster: Waxy to vitreous; Structure: Cryptocrystalline quartz (chalcedony); Specific Gravity: 2.6-2.9.

Hardness: 6
Color: Tan, brown, white, and grey with wood-grain patterns
Luster: Waxy to vitreous

Identified June 29, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Tan, brown, white, and grey with wood-grain patterns; Luster: Waxy to vitreous; Structure: Cryptocrystalline quartz (chalcedony); Specific Gravity: 2.6-2.9.

Formation & geological history

Formed through permineralization where organic wood is replaced by silica-rich minerals (quartz or opal) in anaerobic conditions, typically after being buried by volcanic ash or sediment millions of years ago.

Uses & applications

Used in ornamental items, high-end furniture (slabs), jewelry, lapidary art, and as a popular specimen for geological collections.

Geological facts

The entire process of petrification occurs over millions of years; famous locations include the Petrified Forest National Park in Arizona, which contains trees from the Triassic period (~225 million years old).

Field identification & locations

Identify by looking for visible growth rings, bark textures, or botanical cellular structures preserved in stone. Found in ancient sedimentary layers and river beds. Collectors should check for high-contrast colors and preservation quality.