mineral

Petrified Wood

Silicified Wood (SiO2)

Hardness: 6.5-7 (Mohs); Color: Tan, white, gray, and brown with banding; Luster: Vitreous to waxy; Structure: Cryptocrystalline quartz (Chalcedony/Opal); Cleavage: Fractures conchoidally.

Hardness: 6
Color: Tan, white, gray, and brown with banding
Luster: Vitreous to waxy

Identified June 30, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Tan, white, gray, and brown with banding; Luster: Vitreous to waxy; Structure: Cryptocrystalline quartz (Chalcedony/Opal); Cleavage: Fractures conchoidally.

Formation & geological history

Formed when organic plant material is replaced by silica-rich minerals (permineralization) over millions of years, often in volcanic ash beds or river sediments. This specimen likely dates from the Mesozoic or Cenozoic eras.

Uses & applications

Used primarily in lapidary work for making jewelry, bookends, and decorative sculptures. It is also an important geological study material for paleobotany.

Geological facts

Unlike typical fossils, petrified wood is a three-dimensional representation of the original organic material, often preserving microscopic cell structures so perfectly that the species of tree can be identified.

Field identification & locations

Identify by looking for wood-grain patterns or ring structures. It is often found in badlands or arid regions like Arizona (Petrified Forest National Park) and Washington state. Look for heavy, stone-like texture with conchoidal fractures.