mineral

Blue Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Pale blue, lavender-blue, or translucent gray-blue; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline/cryptocrystalline); Cleavage: None; Fracture: Conchoidal (shell-like curves); Specific Gravity: 2.58–2.64.

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

Identified April 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed at relatively low temperatures in the cavities and fissures of volcanic rocks or sedimentary environments. It is a precipitate from silica-rich groundwater. Most deposits are associated with Tertiary or Quaternary volcanic activity.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and carvings. It is also a popular specimen for collectors and is sometimes used in artisanal jewelry and as a healing stone in metaphysical practices.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen under a standard microscope. Blue chalcedony often displays a characteristic known as the Tyndall effect, where light scattering gives it a glowing, ethereal blue appearance.

Field identification & locations

Identify in the field by its waxy luster, smooth conchoidal fracture, and lack of visible crystal grains. It is commonly found in India, Namibia, Turkey, and the Mojave Desert in the USA. Look for it in weathered volcanic outcrops or in dry riverbeds nearby.