sedimentary
Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown to mustard yellow; Luster: Vitreous to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
- Hardness
- 6
- Color
- Reddish-brown to mustard yellow
- Luster
- Vitreous to waxy
Identified More sedimentary →
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown to mustard yellow; Luster: Vitreous to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91.
Formation & geological history
Primarily formed as a sedimentary rock through the deposition of silica from volcanic ash or hydrothermal fluids into sediments, often during the Precambrian or Paleozoic eras. This specific specimen appears to be a water-worn river pebble.
Uses & applications
Used extensively in jewelry as cabochons, beads, and ornamental carvings. Historically used for seals, vases, and as a decorative stone in architecture.
Geological facts
The name 'Jasper' is derived from the Greek word 'iaspis', meaning spotted stone. It has been a popular gemstone since ancient times and was mentioned in the Bible as a precious stone.
Field identification & locations
Identified in the field by its opacity, smooth water-worn surface (if found in rivers), and its inability to be scratched by a steel knife. Commonly found in gravel beds, beaches, and desert washes throughout western North America.
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