gemstone

Polished druzy agate or chalcedony

Microcrystalline quartz (SiO₂), likely agate with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent milky-gray chalcedony with a glossy polish and rusty orange-brown crystalline/inclusion-filled center. Quartz has a trigonal crystal structure, no cleavage, conchoidal fracture, and specific gravity near 2.6.

Identified August 25, 2026More gemstone →

Explore Polished druzy agate 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

Formed when silica-rich groundwater filled a cavity in volcanic rock, depositing chalcedony and later quartz crystals; iron oxides produced the brown-red coloration. The exact geological age cannot be determined from the image, but agates commonly form in Phanerozoic volcanic flows.

Uses & applications

Used as a tumbled gemstone, cabochon, ornament, and collector specimen; agate is also used for beads, carvings, and decorative objects.

Geological facts

The crystalline cavity is likely a small druzy vug, while the reddish material may be hematite or limonite. Natural agate commonly displays concentric banding, though this specimen appears mostly unbanded.

Field identification & locations

Identify by its waxy-to-glassy luster, translucency, rounded polished form, and resistance to scratching by steel. Common sources include Brazil, Uruguay, Mexico, India, and the western United States.