mineral

Agate (or Chalcedony pebble)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness 6.5-7 on the Mohs scale, waxy to vitreous luster, translucent to opaque with subtle color banding in shades of yellowish-brown and tan, microcrystalline structure, no cleavage, specific gravity ~2.6.

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed through secondary deposition of silica-rich fluids filling cavities (vesicles) within volcanic rocks or sedimentary host rocks, followed by erosion that released the hard pebble.

Uses & applications

Used for lapidary work, tumbling, jewelry making, decorative crafts, and mineral collecting.

Geological facts

Agates are microcrystalline varieties of quartz. Water-worn agates often develop a smooth, rounded surface after being transported by rivers, streams, or glacial movement over thousands to millions of years.

Field identification & locations

Can be identified in the field by its hardness (scratches glass), smooth water-worn texture, translucency when held to light, and characteristic subtle banding or color variations. Commonly found in riverbeds, gravel pits, and coastal areas globally.