mineral

Blue Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5–7 on Mohs scale; Color: Translucent grayish-blue to lavender; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline/cryptocrystalline); Cleavage: None/Conchoidal fracture; Specific Gravity: 2.6

Hardness: 6
Color: Translucent grayish-blue to lavender
Luster: Waxy to vitreous

Identified March 17, 2026More mineral →

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Physical properties

Formation & geological history

Formed by the precipitation of silica from groundwater in volcanic cavities (vugs), sedimentary rocks, or hydrothermal veins. It often forms at relatively low temperatures over millions of years.

Uses & applications

Used primarily in the jewelry industry for cabochons and beads, ornamental carvings, and by collectors. Also historically used for making seals and amulets.

Geological facts

Blue chalcedony is a cryptocrystalline variety of quartz. Its blue color is often the result of the Raleigh scattering of light by microscopic inclusions or fibrous structures within the stone rather than a specific chemical pigment.

Field identification & locations

Identify in the field by its waxy luster, conchoidal (shell-like) fracture, and lack of visible crystals. It is commonly found in Brazil, Namibia, Turkey, and the Southwestern United States. Collectors should look for evenness of color and translucency.