mineral

Polished agate (chalcedony nodule)

Microcrystalline quartz, SiO₂; agate is banded chalcedony, with possible iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent gray, cream, and orange-brown; waxy to vitreous luster; cryptocrystalline quartz with no cleavage and conchoidal fracture. The rounded, polished surface obscures any visible banding, so exact identification is uncertain.

Identified October 13, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited quartz in cavities or fractures, sometimes with iron oxides producing orange-red areas. Agates form in many settings and ages, commonly within volcanic rocks.

Uses & applications

Polished specimens are used for jewelry, cabochons, ornaments, and collecting; agate is also used for small decorative and precision objects.

Geological facts

Agate is a variety of chalcedony rather than a separate mineral species; its colors and patterns result from impurities and deposition conditions.

Field identification & locations

Look for waxy luster, hardness near 7, conchoidal fracture, and—where present—curved or concentric bands. Agates occur worldwide, notably in volcanic regions and sedimentary deposits; this specimen cannot be assigned a locality from the image.