sedimentary
Jasper
Jasper (Silicon Dioxide, SiO2)
Hardness: 6.5–7 on the Mohs scale. Color: Reddish brown, earthy tones. Luster: Dull to greasy. Crystal Structure: Trigonal (as microcrystalline quartz). Cleavage: None (conchoidal fracture). Specific Gravity: 2.6–2.9.
- Hardness
- 6
- Color
- Reddish brown, earthy tones
- Luster
- Dull to greasy
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Physical properties
Hardness: 6.5–7 on the Mohs scale. Color: Reddish brown, earthy tones. Luster: Dull to greasy. Crystal Structure: Trigonal (as microcrystalline quartz). Cleavage: None (conchoidal fracture). Specific Gravity: 2.6–2.9.
Formation & geological history
Formed from silica-rich groundwater or volcanic ash that precipitates and replaces organic materials or other minerals over millions of years. This specimen likely contains high amounts of iron oxide, giving it a brown-red hue.
Uses & applications
Commonly used as a gemstone in necklaces and bracelets, for ornamental carvings, and in industrial applications such as abrasives.
Geological facts
Jasper is an opaque variety of chalcedony. It has been used since antiquity by many civilizations, including the Romans and Egyptians, for seals and amulets due to its durability and rich color.
Field identification & locations
Identify in the field by its hardness (it can scratch glass and steel), opaque appearance (does not let light through), and its characteristic smooth, curved fracture surfaces. Often found in riverbeds or gravel deposits.
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