mineral

Petrified Wood

Silicified Wood (primarily SiO2)

Hardness: 6.5–7 on Mohs scale; Color: Brown, tan, reddish-brown; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6–2.9

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

Identified June 27, 2026More mineral →

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Physical properties

Hardness: 6.5–7 on Mohs scale; Color: Brown, tan, reddish-brown; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6–2.9

Formation & geological history

Formed through permineralization, a process where organic material is replaced by minerals (usually silica) while retaining the original structure. This specimen likely dates from the Mesozoic or Cenozoic eras.

Uses & applications

Commonly used for lapidary work, jewelry (cabochons), interior decor (tabletops, bookends), and as educational geological specimens.

Geological facts

Petrified wood is the state fossil of Arizona. The cell structure of the original tree is often so perfectly preserved that the species of tree can be identified under a microscope.

Field identification & locations

Identify by looking for bark textures and growth rings preserved in a stone that feels heavy and hard like quartz. Commonly found in sedimentary beds where volcanic ash was present, such as in the southwestern United States.