Rock Identifier
Petrified Wood (Silicified Wood (mainly Quartz / SiO2)) — fossil
fossil

Petrified Wood

Silicified Wood (mainly Quartz / SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Tan, beige, brown, grayish-white with faint dark inclusions; Luster: Vitreous to dull; Structure: Cryptocrystalline preserving cellular woody plant structure; Cleavage: None (conchoidal fracture).

Hardness
6
Color
Tan, beige, brown, grayish-white with faint dark inclusions
Luster
Vitreous to dull
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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Tan, beige, brown, grayish-white with faint dark inclusions; Luster: Vitreous to dull; Structure: Cryptocrystalline preserving cellular woody plant structure; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed through permineralization, where organic wood material is buried under sediment or volcanic ash and gradually replaced by silica-rich mineral solutions (such as chalcedony or quartz) over millions of years.

Uses & applications

Used for lapidary arts, decorative polished display pieces, jewelry (cabochons), and popular in mineral and fossil collections.

Geological facts

Petrified wood preserves original structural details of tree trunks and branches down to a microscopic level. Complete fossil forests exist, such as the Petrified Forest National Park in Arizona, USA.

Field identification & locations

Identified by visible growth ring or wood grain textures combined with the hardness and weight of quartz/silica. Commonly found in sedimentary basins and ancient volcanic ash beds globally.

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