mineral

Polished brown agate beads

Microcrystalline quartz (SiO₂), commonly classified as chalcedony; the exact variety cannot be determined from the image

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; glossy polish, brown with subtle banding or cloudy patterns, and no visible cleavage. Agate is microcrystalline quartz, so individual crystals are not visible.

Identified October 3, 2026More mineral →

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Physical properties

Hardness about 6.5–7 Mohs; glossy polish, brown with subtle banding or cloudy patterns, and no visible cleavage. Agate is microcrystalline quartz, so individual crystals are not visible.

Formation & geological history

Forms as silica-rich groundwater deposits concentric or irregular layers in cavities, often in volcanic rock. The beads are cut and polished from natural material; age depends on the source deposit.

Uses & applications

Used in jewelry, beadwork, and decorative objects.

Geological facts

Agate’s fine-grained quartz texture makes it durable and readily polishable; its patterns vary widely between specimens.

Field identification & locations

Look for hardness, waxy-to-glassy luster, and curved or irregular bands; these drilled beads may be dyed or treated, which cannot be confirmed visually. Agate occurs worldwide, including Brazil, Uruguay, India, and the United States.