Mineral

Agate

Agate (Cryptocrystalline Quartz, SiO2)

Hardness 6.5-7 on Mohs scale. Colors can vary widely; this specimen is blue with white banding. Luster is waxy to vitreous. Crystal structure is trigonal/cryptocrystalline. It has no cleavage and a specific gravity of 2.58-2.64.

Identified June 18, 2026More mineral →

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Physical properties

Formation & geological history

Agates typically form within volcanic and metamorphic rocks. Silica-rich fluids fill cavities and over time, deposit layers of chalcedony, creating characteristic banding.

Uses & applications

Commonly used in jewelry, ornamental objects, and talismans. It is highly valued as a semi-precious stone by collectors.

Geological facts

Agate is named after the Achates River in Sicily, where it was first discovered. The banding in agate often reflects the changing composition of the silica-rich fluids during its formation.

Field identification & locations

Identified by its signature curved or distinct banding and waxy luster. It is commonly found globally, notably in the US, Brazil, and India. Collectors value distinct patterns and vibrant colors.