sedimentary
Jasper
Silicon dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Yellow-brown/mustard; Luster: Dull to waxy; Crystal Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific gravity: 2.58-2.91
- Hardness
- 6
- Color
- Yellow-brown/mustard
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow-brown/mustard; Luster: Dull to waxy; Crystal Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific gravity: 2.58-2.91
Formation & geological history
Formed from the deposition of silica from mineral-rich waters, often as a result of chemical precipitation or replacement of organic material. These beach pebbles are often shaped by wave action over millions of years.
Uses & applications
Commonly used for lapidary work, jewelry (cabochons), tumbling for collectors, and ornamental carvings.
Geological facts
Jasper is an opaque variety of chalcedony. The yellow coloring in this specimen is typically caused by goethite or iron oxide inclusions throughout the silica matrix.
Field identification & locations
Identify by its opacity, smooth 'river-rock' texture, and inability to be scratched by a steel knife. Commonly found on pebble beaches world-wide, particularly in the Pacific Northwest.
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