sedimentary
Jasper (Yellow Jasper)
Silicon Dioxide (SiO2) with iron inclusions
Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow to golden brown; Luster: Dull to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91
- Hardness
- 6
- Color
- Mustard yellow to golden brown
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow to golden brown; Luster: Dull to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91
Formation & geological history
Formed from silica-rich fluids that seep through porous sedimentary rock or volcanic ash, replacing minerals over millions of years. Often associated with thermal spring activity or prehistoric ocean floors.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons), as an ornamental stone, and in metaphysical rock collecting.
Geological facts
Jasper is an opaque variety of chalcedony. Yellow jasper specifically gets its coloring from the presence of geothite or iron oxyhydroxide within the quartz structure.
Field identification & locations
Identify by its opacity (it will not let light pass through like agate) and its smooth, waxy feel when tumbled. Common in desert regions of India, Russia, and the Western USA.
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