mineral

Chalcedony (Yellow Agate)

Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Pale yellow to honey gold; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Pale yellow to honey gold
Luster: Waxy to vitreous

Identified May 25, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Pale yellow to honey gold; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58-2.64.

Formation & geological history

Formed primarily in volcanic environments through the deposition of silica from groundwater in cavities of igneous rocks such as basalt. This specimen shows water-worn rounding, suggesting secondary transport in a river or coastal environment.

Uses & applications

Used frequently in jewelry as cabochons or beads, ornamental carvings, and as a collector's specimen. In industry, it was historically used for making precision bearings and mortars.

Geological facts

Chalcedony was highly prized in the ancient world for seal stones because wax does not stick to it. Many yellow agates derive their color from fine dispersions of iron oxide (limonite) within the silica structure.

Field identification & locations

Identified in the field by its translucency, waxy surface texture, and lack of visible crystal faces. Often found in riverbeds, gravel pits, and beaches in volcanic regions.