gemstone

Tumbled agate (likely moss or brecciated agate)

Microcrystalline quartz, mainly chalcedony (SiO₂), with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; rounded and polished, with translucent gray-blue, brown, cream, and rusty-red areas. It has a waxy to vitreous luster, cryptocrystalline structure, and no obvious cleavage; apparent cavities or patches may reflect inclusions or surface wear.

Identified August 14, 2026More gemstone →

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Physical properties

Formation & geological history

Agate forms when silica-rich groundwater fills vesicles in volcanic rock, depositing chalcedony and quartz in layers or patches; iron oxides create the red-brown colors. Formation commonly occurred in ancient basaltic lava flows, ranging from Paleozoic to Cenozoic in age.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and small polished collectibles; larger agate is also used for bookends and decorative slabs.

Geological facts

The specimen appears human-tumbled and may be moss, plume, or brecciated agate rather than a single precisely identifiable variety from the photograph alone.

Field identification & locations

Look for curved banding, translucent edges, waxy luster, and hardness sufficient to scratch ordinary glass; common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. A magnifier and backlighting can reveal chalcedony bands and inclusions.