mineral

Blue Chalcedony (likely dyed)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Hardness: 6.5-7 Mohs scale; Color: Deep blue; Luster: Vitreous to waxy; Crystal structure: Trigonal/Monoclinic (microscopic); Cleavage: None; Specific gravity: 2.6

Hardness: 6
Color: Deep blue
Luster: Vitreous to waxy

Identified March 25, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs scale; Color: Deep blue; Luster: Vitreous to waxy; Crystal structure: Trigonal/Monoclinic (microscopic); Cleavage: None; Specific gravity: 2.6

Formation & geological history

Formed through the deposition of silica from aqueous solutions in volcanic and sedimentary rocks. Naturally occurring blue chalcedony occurs globally, but saturated deep-blue pieces like this cabochon are often enhanced or dyed during the cutting process.

Uses & applications

Primary use is in jewelry (cabochons, beads, rings) and ornamental carvings. It is also a popular specimen for crystal collectors.

Geological facts

Chalcedony has been used since the Bronze Age for seals and amulets. The 'blue' variety is technically 'translucent' and gains its natural tint through the Tyndall effect—the scattering of light by embedded particles.

Field identification & locations

Identify in the field by its conchoidal fracture, lack of cleavage, and ability to scratch glass. Natural sources include Namibia, Turkey, and the USA. For collectors, check the intensity of color; if the color is concentrated in cracks, it is likely dyed.

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