gemstone

Yellow Agate

Silicon Dioxide (Chalcedony variety), SiO2

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

Identified July 30, 2026More gemstone →

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Physical properties

Formation & geological history

Forms primarily in cavities of volcanic and metamorphic rocks through the slow deposition of silica-rich groundwater solutions over millions of years.

Uses & applications

Widely used in making jewelry, ornamental carvings, beads, and polished display specimens.

Geological facts

Agate has been used by humans for thousands of years, dating back to the Neolithic period for amulets and tools. Natural yellow coloring is typically caused by iron oxide impurities within the chalcedony matrix.

Field identification & locations

Can be identified by its microcrystalline structure, conchoidal fracture, and resistance to scratching by steel. Commonly found in Brazil, India, Madagascar, and the United States.

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