sedimentary
Jasper (Petrified Wood variant)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs); Color: Reddish-brown to tan; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9.
- Hardness
- 6
- Color
- Reddish-brown to tan
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Reddish-brown to tan; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9.
Formation & geological history
Formed through permineralization, where organic wood material is replaced by silica-rich water over millions of years. This specimen appears to be a highly jaspellized or agatized piece of fossilized wood from the Mesozoic era.
Uses & applications
Used primarily in lapidary arts for cabochons, jewelry, and decorative carvings. It is also used in landscaping and as a highly sought-after collector gemstone.
Geological facts
Jasper is an opaque variety of chalcedony. In fossilized wood, the red color is almost always due to the presence of hematite or other iron oxides during the fossilization process. Some of the most famous deposits are in the Petrified Forest National Park in Arizona.
Field identification & locations
Identify in the field by its high hardness (cannot be scratched by a steel knife), smooth waxy feel when wet, and characteristic wood-grain or bark-like patterns. Commonly found in eroded river beds or volcanic ash deposits.
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