mineral
Black Jasper (Etched)
Silicon Dioxide (SiO2) with impurities
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale; Color: Deep black with tan/buff etching; Luster: Vitreous to waxy when polished; Crystal Structure: Trigonal (Cryptocrystalline); Cleavage: None (Conchoidal fracture)
- Hardness
- 6
- Color
- Deep black with tan/buff etching
- Luster
- Vitreous to waxy when polished
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Deep black with tan/buff etching; Luster: Vitreous to waxy when polished; Crystal Structure: Trigonal (Cryptocrystalline); Cleavage: None (Conchoidal fracture)
Formation & geological history
Formed from silica-rich fluids depositing in cracks or cavities in volcanic rocks or through the replacement of organic materials. Found in many geological ages from Precambrian to recent.
Uses & applications
Predominantly used for ornamental purposes, jewelry making, beads, and as cabochons for carved decorative objects.
Geological facts
Jasper is an opaque variety of chalcedony. Black jasper was historically used as a 'touchstone' to test the purity of gold and silver because of its hardness and dark surface.
Field identification & locations
Identify by its hardness (will scratch glass), opaque nature, and smooth conchoidal fracture. Often found in stream beds or coastal gravels globally, with significant deposits in India, Egypt, and the USA.
