fossil

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Shades of brown, yellow, beige, tan, red, and dark grey; Luster: Waxy to vitreous; Structure: Cryptocrystalline preserving original organic wood cell structures; Specific Gravity: 2.6-2.8.

Hardness: 6
Color: Shades of brown, yellow, beige, tan, red, and dark grey
Luster: Waxy to vitreous

Identified July 24, 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 lack. Mineral-rich water flowing through the sediment deposits minerals like chalcedony/quartz into the plant's cells.

Uses & applications

Used for making ornamental objects, polished display specimens, lapidary art, jewelry (cabochons), and geological collections.

Geological facts

Over millions of years, all the organic material of the wood is replaced with silicate minerals like quartz, while retaining the original three-dimensional structure of the wood down to the microscopic cellular level.

Field identification & locations

Identified by wood grain patterns, tree ring structures, and bark textures combined with the hardness and weight of quartz rock. Commonly found in Arizona (Petrified Forest National Park), Madagascar, Indonesia, and various river beds worldwide.