mineral

Beach Agate (Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Translucent tan, honey, or ‘carnelian’ orange; Luster: Waxy to vitreous; Crystal structure: Microcrystalline (trigonal); Cleavage: Fractures conchoidally; Specific gravity: 2.6-2.64.

Hardness: 6
Color: Translucent tan, honey, or ‘carnelian’ orange
Luster: Waxy to vitreous

Identified March 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary deposit when silica-rich groundwater fills cavities (vesicles) in volcanic or sedimentary rocks. This specimen has been naturally tumbled and polished by wave action over thousands of years.

Uses & applications

Used in gemstone carving, jewelry (cabochons), and as decorative aquarium or landscaping stones. High-grade specimens are popular among lapidary artists.

Geological facts

Agate is a variety of chalcedony characterized by its translucency and fine grain. Beach agates are often called 'sea glass of the earth' because the ocean naturally smooths their rough edges into rounded pebbles.

Field identification & locations

Identify in the field by its translucency (hold it up to sunlight to see if it glows) and smooth, waxy texture compared to surrounding rocks. Commonly found on Pacific Northwest beaches (USA) and along the shores of the Great Lakes.