mineral

Banded Agate (Onyx type)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Black with white/grey bands; Luster: Vitreous to waxy; Crystal structure: Trigonal (cryptocrystalline); Specific gravity: 2.58-2.64

Hardness: 6
Color: Black with white/grey bands
Luster: Vitreous to waxy

Identified July 1, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Black with white/grey bands; Luster: Vitreous to waxy; Crystal structure: Trigonal (cryptocrystalline); Specific gravity: 2.58-2.64

Formation & geological history

Formed in cavities of volcanic rock (basalt) or ancient lava flows as silica-rich water percolates through voids, depositing layers of microcrystalline quartz over thousands of years.

Uses & applications

Widely used in jewelry (rings, pendants), carvings, decorative ornaments, and as tumbled stones for metaphysical collecting.

Geological facts

The distinct banding is caused by rhythmic crystallization pulses. When the bands are parallel and black/white, it is specifically referred to as Onyx.

Field identification & locations

Identify by its waxy luster and the presence of fine, concentric or parallel banding. It is often found in riverbeds or coastal areas where volcanic rocks have weathered away. Common in Brazil, India, and the Lake Superior region of the US.