metamorphic
Petrified Wood
Silicified Wood (SiO2)
Hardness: 6.5–7 on the Mohs scale. Color: Multicolored (red, orange, yellow, brown, white). Luster: Vitreous to waxy. Crystal structure: Cryptocrystalline (chalcedony/quartz). Cleavage: None; conchoidal fracture. Specific gravity: 2.6–2.9.
- Hardness
- 6
- Color
- Multicolored (red, orange, yellow, brown, white)
- Luster
- Vitreous to waxy
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5–7 on the Mohs scale. Color: Multicolored (red, orange, yellow, brown, white). Luster: Vitreous to waxy. Crystal structure: Cryptocrystalline (chalcedony/quartz). Cleavage: None; conchoidal fracture. Specific gravity: 2.6–2.9.
Formation & geological history
Formed through permineralization over millions of years (often Triassic, 200+ million years ago). Organic plant material is replaced by silica-rich groundwater under anaerobic conditions, preserving the cellular structure of the original tree.
Uses & applications
Used in lapidary work for jewelry, bookends, furniture, and as high-value cabinet specimens for collectors.
Geological facts
Trace elements determine the colors: iron oxides yield reds and yellows, while manganese oxides create blues and purples. The Petrified Forest National Park in Arizona contains one of the world's largest concentrations.
Field identification & locations
Identify in the field by looking for distinct tree rings or bark texture on rock that has the weight and feel of quartz. Found in sedimentary basins globally, specifically in Arizona and Madagascar.
More like this
