mineral

Banded Black Agate

Silicon Dioxide (SiO2)

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

Hardness: 6
Color: Alternating bands of black, grey, and white
Luster: Vitreous to waxy

Identified July 18, 2026More mineral →

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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.