mineral

Blue Chalcedony (Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Translucent to opaque light blue; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Translucent to opaque light blue
Luster: Waxy to vitreous

Identified June 16, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Translucent to opaque light blue; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64.

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of volcanic and sedimentary rocks. These specimens represent cryptocrystalline quartz that often forms in low-temperature hydrothermal environments.

Uses & applications

Primarily used in jewelry (beads, cabochons), ornamental carvings, and as a collector's gemstone. Also used in metaphysical practices.

Geological facts

Chalcedony was used as early as the Bronze Age in the Mediterranean region for seals and jewelry. The 'blue' variety is often artificially enhanced with dyes to achieve the uniform, vibrant saturation seen in many commercial beads.

Field identification & locations

Identify by its waxy luster, lack of cleavage, and smooth, conchoidal fracture. In the field, it is often found as nodules or lining geodes. Common locations include Brazil, Namibia, and the USA (Oregon/California).