sedimentary
Black Jasper
Silicon Dioxide (SiO2) with Carbonaceous inclusions
Hardness: 6.5-7.0 (Mohs scale), Color: Jet black with white/grey veins, Luster: Vitreous to waxy, Crystal Structure: Trigonal (Microcrystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.58-2.91
- Hardness
- 6
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Physical properties
Hardness: 6.5-7.0 (Mohs scale), Color: Jet black with white/grey veins, Luster: Vitreous to waxy, Crystal Structure: Trigonal (Microcrystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the infiltration of silica in volcanic ash or fine-grained sediments. The black color is typically caused by organic matter or carbonaceous inclusions during the lithification process.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons), talismans, and as polished decorative or meditation stones.
Geological facts
Black Jasper is sometimes specifically referred to as 'Basanite' or 'Lydian Stone' when used as a touchstone to test the purity of gold or silver. Unlike many other stones, jasper is opaque and does not transmit light even at the thin edges.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife), smooth conchoidal fracture, and absolute opacity. It is commonly found in India, Russia, Brazil, and the Southwestern USA.
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