mineral

Agate

Silicon dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Honey yellow to translucent tan; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64

Hardness: 6
Color: Honey yellow to translucent tan
Luster: Waxy to vitreous

Identified May 24, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Honey yellow to translucent tan; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64

Formation & geological history

Formed in cavities within volcanic or sedimentary rocks, where silica-rich groundwater deposits layers of microcrystalline quartz over thousands of years.

Uses & applications

Commonly used in jewelry, ornamental carvings, lapidary art, and collected for its aesthetic banding and colors.

Geological facts

Agate is named after the Achates River in Sicily where it was first discovered in ancient times. It has been used for talismans and decorations for over 3,000 years.

Field identification & locations

Identify in the field by its waxy appearance, conchoidal fracture (smooth, curved breaks), and transparency when held to light. Often found in riverbeds or volcanic fields.