mineral

Agate (Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Translucent tan to orange-red (carnelian-tinged). Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Translucent tan to orange-red (carnelian-tinged)
Luster: Waxy to vitreous

Identified June 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities of volcanic rocks or ancient sedimentary formations where silica-rich groundwater deposits layers of rhythmic crystallization over thousands of years.

Uses & applications

Used in gemstone jewelry (cabochons), interior decor, burnishing tools, and as a popular specimen for rock collectors and lapidary hobbyists.

Geological facts

Agate is a variety of chalcedony characterized by its transparency and color banding. The orange hues are often caused by the inclusion of iron oxides during formation.

Field identification & locations

Identify in the field by its waxy appearance, smooth conchoidal (shell-like) fractures, and translucency when held to light. Commonly found in riverbeds and volcanic regions worldwide.