mineral

Tumbled agate or chalcedony pebble

Microcrystalline quartz, SiO₂ (likely iron-stained chalcedony/agate)

AI-generated identification · may be incorrect

Translucent honey-brown to orange, with waxy luster and irregular pale banding or fracture patterns; quartz hardness is about 7 Mohs, lacks cleavage, and has specific gravity near 2.6. The rounded shape indicates natural abrasion or tumbling.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rock, commonly producing layered chalcedony and iron-oxide coloration. The specimen’s exact geological age cannot be determined from the photograph; agates range from Paleozoic to modern volcanic settings.

Uses & applications

Used as a lapidary stone for cabochons, beads, carvings, and decorative objects; small tumbled pieces are common collector items.

Geological facts

Agate is a variety of chalcedony distinguished by microscopic quartz growth and commonly visible banding. Orange-brown color typically reflects hematite or goethite inclusions.

Field identification & locations

Identify by glassy-to-waxy appearance, translucency, hardness, and inability to scratch it with a steel nail; quartz should scratch ordinary glass. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States.