Banded Agate (Gray/White)

Physical Properties

Hardness: 6.5-7 on Mohs scale. Color: Translucent gray and white bands. Luster: Waxy to vitreous. Crystal structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None. Specific gravity: 2.58-2.64.

Formation & Geological History

Formed in cavities within volcanic rocks or ancient lavas, through the deposition of silica from groundwater. These nodules can be millions of years old, often found in Cenozoic basalts.

Uses & Applications

Commonly used for tumbled stones, decorative ornaments, jewelry (cabochons), and mortar and pestles due to its hardness and resistance to chemicals.

Geological Facts

Agate was named by the Greek philosopher Theophrastus after the Achates River in Sicily where it was first discovered. Every agate is unique—no two banded patterns are exactly alike.

Field Identification & Locations

Identify by its waxy luster, translucent edges, and distinct banding pattern when held to light. Common in riverbeds and areas with past volcanic activity like Brazil, India, and the Lake Superior region.

Identified on: 4/18/2026

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