mineral

Banded Agate

Agate (Silicon Dioxide, SiO2)

Hardness: 6.5-7 Mohs; Color: Varied bands of grey, blue-grey, and white; Luster: Vitreous to waxy; Crystal structure: Trigonal (cryptocrystalline); Specific gravity: 2.58-2.64.

Hardness: 6
Color: Varied bands of grey, blue-grey, and white
Luster: Vitreous to waxy

Identified June 8, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Varied bands of grey, blue-grey, and white; Luster: Vitreous to waxy; Crystal structure: Trigonal (cryptocrystalline); Specific gravity: 2.58-2.64.

Formation & geological history

Formed in cavities of volcanic rocks (lavas) or certain metamorphic rocks through the deposition of silica from groundwater. The bands are formed by successive layers of silica being deposited over millennia.

Uses & applications

Used widely in lapidary arts for jewelry, decorative ornaments, bookends, and collection. Historically used for making hardstone carvings and precision instrument bearings.

Geological facts

The name 'Agate' comes from the Achates River in Sicily, where agates were first discovered. Unlike many minerals, the banding in agate is caused by rhythmic crystallization.

Field identification & locations

Identify in the field by its characteristic concentric banding, waxy luster when broken, and extreme hardness (it will scratch glass). Commonly found in river beds, beaches, and volcanic regions.