sedimentary
Jasper (Petrified Wood Variety)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Pink, purple, tan, and reddish-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
- Hardness
- 6
- Color
- Pink, purple, tan, and reddish-brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Pink, purple, tan, and reddish-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
Formation & geological history
Formed through the process of permineralization, where organic wood material is replaced by silica-rich water over millions of years. This piece likely dates from the Triassic period (approx. 225 million years ago).
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), interior decoration (bookends, tabletops), and as a popular collector's specimen.
Geological facts
The vibrant pink and purple hues in this specimen are often caused by trace amounts of manganese or iron oxides during the agatization process. Famous deposits include the Petrified Forest National Park in Arizona.
Field identification & locations
Identify by its heavy weight, woody texture often visible on the outer 'bark' layer, and characteristic conchoidal (shell-like) fractures on smooth surfaces. It cannot be scratched by a steel knife.
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