gemstone

Polished agate or chalcedony nodule

Microcrystalline quartz (SiO₂), likely agate/chalcedony

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; cream-white, translucent to opaque, with faint concentric banding and a gray-blue central area. Waxy to vitreous luster and cryptocrystalline quartz structure; no obvious cleavage, conchoidal fracture.

Identified August 23, 2026More gemstone →

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Physical properties

Formation & geological history

Silica-rich groundwater deposited chalcedony in a cavity or vesicle, commonly in volcanic rock; later erosion and human polishing exposed the interior. Exact geological age and locality cannot be determined from the image.

Uses & applications

Used for cabochons, beads, carvings, lapidary specimens, and decorative objects; agate is also used for durable ornaments and occasional industrial abrasives.

Geological facts

The specimen may be a small polished agate nodule or a druzy/geode fragment, but visible banding is too limited for a definitive variety identification.

Field identification & locations

Field clues include waxy translucency, curved banding, conchoidal fracture, and resistance to scratching by steel; quartz should scratch ordinary glass. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States.