gemstone

Yellow Agate

Silicon Dioxide (Chalcedony), SiO2

Hardness of 6.5 to 7 on the Mohs scale, yellow to orange color, waxy to vitreous luster, microcrystalline (cryptocrystalline) crystal structure, conchoidal fracture with no true cleavage, specific gravity of 2.58 to 2.64.

Identified August 5, 2026More gemstone →

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Physical properties

Formation & geological history

Formed within the cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater solutions over millions of years.

Uses & applications

Used primarily in jewelry, ornamental carvings, polished specimens, and lapidary art.

Geological facts

Agate has been used by humans for thousands of years, dating back to Neolithic times for tools and ornamentation, and was highly prized in ancient Greece and Rome for signet rings.

Field identification & locations

Easily identified by its waxy luster, microcrystalline texture, and hardness that can scratch glass. Commonly found in riverbeds, beaches, and volcanic regions worldwide.