mineral

Blue Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Pale blue, lavender-blue; Luster: Vitreous to waxy; Structure: Cryptocrystalline (Trigonal/Monoclinic); Cleavage: None; SG: 2.6

Hardness: 6
Color: Pale blue, lavender-blue
Luster: Vitreous to waxy

Identified April 14, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Pale blue, lavender-blue; Luster: Vitreous to waxy; Structure: Cryptocrystalline (Trigonal/Monoclinic); Cleavage: None; SG: 2.6

Formation & geological history

Formed in volcanic cavities or sedimentary environments via silica-rich water precipitation. It occurs as a secondary mineral in igneous rocks or as a replacement mineral in petrified wood.

Uses & applications

Predominantly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a collector's specimen.

Geological facts

In antiquity, it was often used for seals and amulets. Significant historical deposits were found in the ancient Greek town of Chalcedon. Some specimens show a slight 'adularescence' similar to moonstone.

Field identification & locations

Identify by its waxy luster, translucency, and lack of visible crystal grains. Common locations include Namibia, Turkey, India, and the USA (California/Oregon). It is harder than glass but won't show the cleavage plane found in blue lace agate.