fossil

Petrified Wood

Silicified wood (primarily quartz, SiO2)

Hardness of 7 on the Mohs scale; colors range from brown, tan, and grey to red and yellow due to mineral impurities; vitreous to waxy luster; cryptocrystalline quartz structure; specific gravity around 2.5-2.7.

Identified August 7, 2026More fossil →

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Physical properties

Formation & geological history

Formed when organic plant material is buried in an oxygen-depleted environment under sediment and slowly replaced by minerals (usually silica) over millions of years, often dating from the Triassic period or younger.

Uses & applications

Used for lapidary work, making decorative objects, jewelry, bookends, furniture tops, and as collector specimens.

Geological facts

Petrified wood can preserve the original cellular structure of the tree down to microscopic details. The Petrified Forest National Park in Arizona is one of the most famous localities in the world for these fossils.

Field identification & locations

Identify by observing typical wood grain and bark textures combined with stone-like weight, coldness, and hardness that can scratch glass. Found worldwide in sedimentary rock layers associated with ancient river floodplains and volcanic ash deposits.

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