mineral

Polished carnelian agate

Chalcedony, microcrystalline quartz (SiO₂), with iron-oxide color bands

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; glossy, opaque-to-translucent gray-white chalcedony with rusty orange-red patches. Cryptocrystalline quartz; no visible cleavage and conchoidal fracture when broken. The exact variety is uncertain from the photograph.

Identified October 14, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited microscopic quartz in cavities and fractures; iron oxides produced the orange coloration. Such agate commonly forms in volcanic rocks, across a wide range of geological ages.

Uses & applications

Polished stones are used for jewelry, ornaments, and collecting; agate also serves in some precision components and decorative objects.

Geological facts

Agate is a banded or patterned variety of chalcedony, and its colors and patterns can vary greatly even within one deposit.

Field identification & locations

Identify by its waxy-to-glassy polish, hardness, and typically non-granular, patterned appearance; common sources include Brazil, Uruguay, India, and the United States. A small tumbled specimen of this size typically sells for about $2–$10 USD.