sedimentary
Jasper (Iron-rich Chert)
Silicon Dioxide (SiO2) with impurities of Hematite or Goethite
Hardness: 6.5–7 (Mohs scale); Color: Yellow, orange, and deep red bands; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91.
- Hardness
- 6
- Color
- Yellow, orange, and deep red bands
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Yellow, orange, and deep red bands; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91.
Formation & geological history
Formed from the deposition of silica-rich fluids in volcanic ash or sedimentary beds, often enriched with iron oxides. This piece appears to have formed in a hydrothermal or marine sedimentary environment during various geological eras (Paleozoic to Cenozoic).
Uses & applications
Commonly used as a gemstone for jewelry (cabochons), ornamental carvings, stone seals, and as decorative gravel. Historically used for making flint-like tools due to its hardness and fracture pattern.
Geological facts
The name 'Jasper' originates from the Greek word 'iaspis', meaning spotted stone. It is a dense, opaque variety of quartz that can hold a very high polish. Its colors are dictated by the oxidation state of the iron within the silica matrix.
Field identification & locations
Identify in the field by its hardness (will scratch glass), opaque nature, and smooth conchoidal fracture. Often found in riverbeds, glacial deposits, or near volcanic regions. This specific specimen shows brecciated or orbicular-like patterns common in jasper-rich terrains like Oregon or Indonesia.
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