sedimentary
Black Jasper
Silicon Dioxide (SiO2) with impurities
Hardness: 6.5-7 on Mohs scale; Color: Black with occasional white or grey veining; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.9.
- Hardness
- 6
- Color
- Black with occasional white or grey veining
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Black with occasional white or grey veining; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.9.
Formation & geological history
Formed through the deposition of silica from water into cavities or via the replacement of organic or volcanic materials. Found often in hydrothermal veins or sedimentary environments across many geological ages.
Uses & applications
Used primarily as a gemstone for jewelry, in lapidary arts for decorative carvings, and as a popular stone for tumbling and collecting.
Geological facts
Also known as Blackstone or Basanite (historically used as a touchstone to test for gold and silver quality). Jasper is the dense, opaque form of chalcedony.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel knife), opaque density, and smooth, conchoidal fracture. Commonly found in riverbeds or coastal areas where quartz-rich minerals accumulate.
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