mineral

Agate

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5–7 on Mohs scale; Color: Multi-colored bands, translucent to opaque; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Fracture: Conchoidal.

Hardness: 6
Color: Multi-colored bands, translucent to opaque
Luster: Waxy to vitreous

Identified June 19, 2026More mineral →

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Physical properties

Hardness: 6.5–7 on Mohs scale; Color: Multi-colored bands, translucent to opaque; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Fracture: Conchoidal.

Formation & geological history

Formed primarily in volcanic and metamorphic rocks as silica-rich groundwater fills gas cavities (vesicles). Over time, layers of microcrystalline quartz deposit on the walls of these cavities, creating banding.

Uses & applications

Commonly used for artisanal jewelry, decorative carvings, beads, and heavy-duty industrial mortars and pestles due to its hardness and chemical resistance.

Geological facts

The name 'Agate' comes from the Achates River in Sicily, where stones were found in ancient times. No two agates are exactly alike due to the unique chemical inclusions during their formation.

Field identification & locations

Identified in the field by its waxy texture and translucency when held to light. Often found in riverbeds or near ancient volcanic sites in regions like the Lake Superior area, Brazil, and India.