mineral
Banded Black Agate
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Alternating bands of black, grey, and white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58-2.64
- Hardness
- 6
- Color
- Alternating bands of black, grey, and white
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Alternating bands of black, grey, and white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58-2.64
Formation & geological history
Formed in volcanic cavities or sedimentary pockets where silica-rich groundwater deposits layers over thousands of years. This specimen is polished/tumbled into a bead or worry stone shape.
Uses & applications
Used primarily in jewelry (beads, pendants), healing crystal practices, and as ornamental decorative pieces.
Geological facts
Black agate is often actually dyed to achieve a deep solid black color, though natural banded black and grey agate is common. It is a variety of chalcedony.
Field identification & locations
Identify by the presence of concentric or parallel banding (stripes) and its ability to scratch glass. Found globally, with high concentrations in Brazil and India.
