gemstone

Tumbled brown agate

Microcrystalline quartz (chalcedony), SiO₂; likely brown banded agate

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent to opaque brown with subtle bands and a polished, waxy-to-glassy luster. Trigonal quartz crystals occur as microscopic fibers; no obvious cleavage, with conchoidal fracture.

Identified October 11, 2026More gemstone →

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Physical properties

Formation & geological history

Silica-rich fluids deposited layers of chalcedony in a cavity, commonly in volcanic rock; the specimen was later tumbled and polished. Agates form across many geological ages.

Uses & applications

Used for jewelry, beads, ornaments, and lapidary collecting; agate is also used for decorative objects and precision components.

Geological facts

Agate’s fine, often concentric banding records successive silica deposition and can be enhanced or obscured by cutting and polishing.

Field identification & locations

Look for translucence, waxy luster, hardness, and curved or parallel bands; common sources include Brazil, Uruguay, India, and the United States. This small polished piece appears consistent with brown agate, though the image cannot confirm its identity.