mineral

Blue Chalcedony

Chalcedony (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Grayish-blue, lavender-blue; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline (trigonal); Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.60-2.65.

Hardness: 6
Color: Grayish-blue, lavender-blue
Luster: Waxy to vitreous

Identified July 15, 2026More mineral →

Explore Blue Chalcedony in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed by the deposition of silica from groundwater in cavities of igneous rocks such as basalt, or in sedimentary environments. Its blue color is caused by the Tyndall effect (light scattering) rather than chemical impurities.

Uses & applications

Used primarily in jewelry as cabochons or beads, ornamental carvings, and as a healing stone in holistic practices. Traditionally used as a semi-precious gemstone.

Geological facts

Chalcedony has been used for centuries to carve seals and talismans. Famous historical deposits include the 'Blue Holly' from Oregon and the high-quality deposits in Namibia (African Blue).

Field identification & locations

Identify by its waxy luster, lack of cleavage, and translucent blue-gray hue. Commonly found in Namibia, Turkey, India, and the United States (western states). Field identification often relies on its hardness and smooth, water-worn appearance when found as a pebble.