mineral

Tumbled brown agate (possible carnelian or chalcedony)

Microcrystalline quartz, SiO₂; agate is banded chalcedony

AI-generated identification · may be incorrect

Smooth, polished, translucent-to-opaque brown stone with a glossy luster. Quartz hardness is about 6.5–7 Mohs; its crystals are microscopic, so cleavage is absent and fracture is typically conchoidal. The image does not show enough detail to confirm banding or distinguish agate from other brown chalcedony.

Identified September 23, 2026More mineral →

Explore Tumbled brown agate (possible carnelian or chalcedony) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms as silica-rich fluid deposits in cavities, commonly in volcanic rocks; colors arise from trace impurities. Such deposits occur across many geological ages and regions.

Uses & applications

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

Geological facts

Agate is valued for varied colors and patterns, but the visible specimen appears uniformly brown and may be another chalcedony variety.

Field identification & locations

Check for translucent edges, waxy luster, and—if present—curved or concentric bands; hardness testing or close inspection can help confirm quartz. Agate is common worldwide, including Brazil, Uruguay, India, and the United States.