Blue Chalcedony

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Pale blue, lavender-blue, or grayish-blue; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline/cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & Geological History

Formed through the deposition of silica from water in cavities or fissures in volcanic rocks or sedimentary environments. It is often associated with volcanic activity and can be found in geodes or as botryoidal masses.

Uses & Applications

Used primarily in jewelry as cabochons, beads, and carvings. Also popular as a collector's specimen and in metaphysical practices.

Geological Facts

Blue Chalcedony is a cryptocrystalline variety of quartz. In ancient times, it was believed to ward off evil spirits and was often used in the making of seals and cameos in Rome and Greece.

Field Identification & Locations

Identify in the field by its waxy luster, translucency, and lack of visible crystals. It is commonly found in Turkey, Namibia, India, and the United States (Oregon/California). To distinguish from glass, look for natural inclusions and consistent hardness.

Identified on: 4/22/2026

Mode: Standard