Rock Identifier
Blue Chalcedony (Silicon Dioxide (SiO2) - Cryptocrystalline Quartz) — mineral
mineral

Blue Chalcedony

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Hardness: 6.5-7 (Mohs scale); Color: Light blue to lavender-blue; Luster: Vitreous to waxy; Crystal structure: Trigonal/Monoclinic (microscopic); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness
6
Color
Light blue to lavender-blue
Luster
Vitreous to waxy
Identified More mineral

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Light blue to lavender-blue; Luster: Vitreous to waxy; Crystal structure: Trigonal/Monoclinic (microscopic); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed through the deposition of silica-rich water in cavities of volcanic igneous rocks or sedimentary environments. It develops at low temperatures over millions of years as microcrystalline fibers.

Uses & applications

Commonly used in jewelry (cabochons, beads), decorative carvings, and as a healing stone in metaphysical practices. It is also a popular collector's specimen.

Geological facts

Blue Chalcedony is often translucent. The 'blue' color is typically the result of the Tyndall effect—the scattering of light by microscopic particles—rather than a specific chemical pigment.

Field identification & locations

Identify in the field by its waxy luster, conchoidal (shell-like) fracture patterns, and lack of visible crystal faces. Note its hardness prevents it from being scratched by a steel knife. Common locations include Namibia, Turkey, Malawi, and the USA (Oregon/California).