mineral

Yellow Agate / Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Translucent yellow to honey-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64

Hardness: 6
Color: Translucent yellow to honey-brown
Luster: Vitreous to waxy

Identified April 8, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. Can occur in sedimentary environments as nodules or veins over millions of years.

Uses & applications

Used primarily in lapidary arts for jewelry, beads, and cabochons. Also used as a decorative stone in home decor and by collectors for its translucency and color.

Geological facts

Yellow agate is a variety of chalcedony that gets its color from finely dispersed iron hydroxides like goethite within the silica matrix. Agates have been used as amulets since ancient Greek and Egyptian times.

Field identification & locations

Identify in the field by its waxy luster, translucency when held to light, and its inability to be scratched by a steel knife. It is commonly found in riverbeds or volcanic regions globally, such as Brazil, India, and the USA.