sedimentary
Black Jasper
Silicon Dioxide (SiO2) with carbon/iron impurities
Hardness: 6.5-7 (Mohs); Color: Black with grey or white veining; Luster: Vitreous to dull; Crystal structure: Trigonal (Microcrystalline); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Black with grey or white veining
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Black with grey or white veining; Luster: Vitreous to dull; Crystal structure: Trigonal (Microcrystalline); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the deposition of silica from water solutions into fissures or volcanic ash, occurring in various geological ages often in association with volcanic activity.
Uses & applications
Commonly used in jewelry (beads, cabochons), protective amulets, decorative carvings, and as a tumbling stone for collectors.
Geological facts
Black Jasper is sometimes known as 'Basanite' and has been historically used as a touchstone to test the purity of gold and silver because of its hardness and dark color.
Field identification & locations
Found worldwide, notably in India, USA, and Africa. Identification features include its smooth, waxy texture and inability to be scratched by a steel knife.
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