mineral

Tumbled brown agate

Microcrystalline quartz (chalcedony), SiO₂; likely iron-oxide colored

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; brown to amber with a waxy-to-glassy luster and translucent edges. Trigonal quartz microcrystals form a fine-grained mass; no visible cleavage and conchoidal fracture. The polished surface obscures any banding, so the exact variety is uncertain.

Identified October 16, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater deposited chalcedony in rock cavities, with iron oxides producing the brown coloration. Agates form in diverse volcanic and sedimentary settings over geological time; this specimen’s age and locality cannot be determined from the image.

Uses & applications

Commonly tumbled for jewelry, décor, and collections; chalcedony is also used for carvings and ornamental objects.

Geological facts

Agate is a variety of chalcedony, not a single distinct mineral species; many agates display concentric bands, though some are nearly unbanded.

Field identification & locations

Identify by its smooth polish, translucent amber-brown edges, and hardness; a scratch test or close inspection for bands can help distinguish it from softer lookalikes. Agates occur worldwide, including Brazil, Uruguay, India, and the western United States.