Rock Identifier
Petrified Wood (Silicified Wood (Permineralized organic matter, głównie $SiO_2$)) — fossil
fossil

Petrified Wood

Silicified Wood (Permineralized organic matter, głównie $SiO_2$)

Hardness: 6.5-7 on the Mohs scale. Color: Brown, tan, reddish, and sometimes multicolored. Luster: Vitreous to dull. Crystal structure: Microcrystalline quartz (chalcedony/jasper). Cleavage: None (conchoidal fracture). Specific gravity: 2.5-2.7.

Hardness
6
Color
Brown, tan, reddish, and sometimes multicolored
Luster
Vitreous to dull
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Physical properties

Hardness: 6.5-7 on the Mohs scale. Color: Brown, tan, reddish, and sometimes multicolored. Luster: Vitreous to dull. Crystal structure: Microcrystalline quartz (chalcedony/jasper). Cleavage: None (conchoidal fracture). Specific gravity: 2.5-2.7.

Formation & geological history

Formed when plant material is buried in an oxygen-depleted environment (such as mud or volcanic ash) and groundwater rich in dissolved minerals flows through the cells, replacing organic matter with silica over millions of years.

Uses & applications

Used for ornamental objects, lapidary work, jewelry, bookends, table tops, and prized as a collector's specimen.

Geological facts

Some petrified wood logs can preserve cellular structures so well that microscopic details of the ancient tree rings and bark can be studied. The Petrified Forest National Park in Arizona is one of the most famous sites in the world.

Field identification & locations

Identify by its woody texture combined with a stone-like weight, hardness, and conchoidal fracture. Commonly found in sedimentary rock layers worldwide where ancient forests once grew, particularly in arid regions with extensive badlands exposure.

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