mineral

Yellow Chalcedony (Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Pale yellow to honey gold with visible banding; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline/Trigonal; Cleavage: None; Specific Gravity: 2.58-2.64

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

Identified June 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of igneous rocks, particularly volcanic basalts, or occasionally in sedimentary environments. Most specimens are millions of years old.

Uses & applications

Used primarily in lapidary arts for jewelry, decorative carvings, and as a semi-precious collector stone. Historically used for making tools and seals.

Geological facts

Yellow chalcedony is often classified as an agate when it exhibits distinctive banding. It is a 'microcrystalline' form of quartz, meaning its crystals are too small to be seen without high magnification.

Field identification & locations

Identify in the field by its waxy luster, conchoidal (shell-like) fracture, and translucent edges. It will easily scratch glass. Commonly found in riverbeds, volcanic regions, and desert pavements.