mineral

Blue Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Pale blue, lavender-blue, or grey-blue; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.60-2.65

Hardness: 6
Color: Pale blue, lavender-blue, or grey-blue
Luster: Waxy to vitreous

Identified July 3, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Pale blue, lavender-blue, or grey-blue; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.60-2.65

Formation & geological history

Formed in volcanic and sedimentary environments through the deposition of silica from hydrothermal fluids or groundwater at relatively low temperatures. Often found in cavities of igneous rocks.

Uses & applications

Predominantly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal healing and mineral collectors.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen without high magnification. The blue variety is prized for its serene color and translucency.

Field identification & locations

Identify by its waxy luster, lack of visible crystals, and conchoidal fracture. Often found in pockets of basalts or as nodules. Common locations include Namibia, Turkey, India, and the United States (Oregon).