mineral

Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale). Color: Multicolored banding in translucent tan, white, and orange. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline (Trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Multicolored banding in translucent tan, white, and orange
Luster: Waxy to vitreous

Identified June 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral in volcanic rock cavities (vugs) or ancient sedimentary rocks. Silica-rich groundwater precipitates layers of microscopic quartz crystals over time, often filling gas bubbles in cooling lava.

Uses & applications

Used primarily in lapidary arts for jewelry, figurines, and beads. Also used in industry for mortar and pestles due to its hardness, and highly valued as a collectible mineral specimen.

Geological facts

The word Agate comes from the Achates River in Sicily, where agates were first discovered. Unlike most minerals, its unique banding pattern makes every single specimen one-of-a-kind.

Field identification & locations

Identify in the field by its characteristic concentric or planar banding visible on weathered surfaces and its ability to scratch glass. Commonly found in areas with past volcanic activity or in riverbeds. Collectors should look for 'fortification' patterns.