mineral

Blue Chalcedony

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 (Mohs); Color: Pale blue, lavender, or grey-blue; Luster: Waxy to vitreous; Structure: Cryptocrystalline (hexagonal/trigonal); Cleavage: None; Specific Gravity: 2.58-2.64.

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

Identified June 21, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Pale blue, lavender, or grey-blue; Luster: Waxy to vitreous; Structure: Cryptocrystalline (hexagonal/trigonal); Cleavage: None; Specific Gravity: 2.58-2.64.

Formation & geological history

Formed via precipitation from silica-rich groundwater in cavities of volcanic and sedimentary rocks. Common in basaltic geodes and hydrothermal veins.

Uses & applications

Used extensively in jewelry as cabochons, decorative carvings, and meditation stones for its soothing aesthetic.

Geological facts

Chalcedony has been used since the Bronze Age for seals and amulets. It is named after the ancient Greek town of Chalcedon in Asia Minor.

Field identification & locations

Identify by its characteristic waxy luster and lack of visible crystals. It is frequently found in India, Brazil, Madagascar, and the United States (Oregon and California).