mineral

Blue Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5–7 (Mohs); Color: Pale blue to translucent lavender; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline/Trigonal; Cleavage: None; Specific Gravity: 2.58–2.64

Hardness: 6
Color: Pale blue to translucent lavender
Luster: Waxy to vitreous

Identified March 25, 2026More mineral →

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Physical properties

Hardness: 6.5–7 (Mohs); Color: Pale blue to translucent lavender; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline/Trigonal; Cleavage: None; Specific Gravity: 2.58–2.64

Formation & geological history

Formed through the deposition of silica from hydrothermal solutions or the weathering of volcanic rocks at low temperatures. It typically occurs as fillings in amygdales (cavities) or as crusts in host rocks like basalt.

Uses & applications

Primarily used in jewelry as cabochons, beads, and carvings. Also popular among mineral collectors and used in metaphysical practices for its purported soothing qualities.

Geological facts

In antiquity, it was often used for seal stones and amulets. The name is believed to come from the ancient Greek port city of Chalcedon. Unlike crystalline quartz (like amethyst), chalcedony is composed of microscopic fibers.

Field identification & locations

Identify in the field by its waxy luster, conchoidal fracture (curved surfaces like glass), and lack of visible crystals. Commonly found in Namibia, Turkey, Malawi, and the United States (Oregon/California).