mineral

Petrified Wood

Silicified Wood (primarily Quartz or Chalcedony, SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, reddish-brown, grey; Luster: Waxy to vitreous; Structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Brown, tan, reddish-brown, grey
Luster: Waxy to vitreous

Identified June 16, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, reddish-brown, grey; Luster: Waxy to vitreous; Structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.9

Formation & geological history

Formed through permineralization, a process where organic material is replaced by silica-rich minerals (often from volcanic ash) over millions of years. This specimen likely dates to the Eocene or Miocene epochs given its reported location.

Uses & applications

Used for ornamental carvings, lapidary work, jewelry, and as highly sought-after display specimens for collectors.

Geological facts

This specimen shows distinct vertical wood grain and bark-like texture preserved in stone. The location provided (near Eugene, Oregon) is part of a volcanic region where ancient forests were buried by ash, leading to high-quality petrification.

Field identification & locations

Identify by looking for distinct cellular structures, tree rings, or bark textures on a slab of stone that is harder than steel. Commonly found in areas with past volcanic activity and sedimentary basins.

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