mineral

Blue Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Pale blue to lavender; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6

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

Identified April 6, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Pale blue to lavender; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6

Formation & geological history

Formed from the deposition of silica from water in cavities or fissures of volcanic or sedimentary rocks. It belongs to the microcrystalline variety of quartz.

Uses & applications

Used primarily in lapidary arts, jewelry (cabochons and beads), and as ornamental carvings or collector specimens.

Geological facts

Chalcedony was highly valued in antiquity and was used by the Minoans in the Mediterranean for making seal stones as early as 1800 BCE.

Field identification & locations

Identify by its waxy luster, conchoidal fracture, and lack of visible crystal faces. Often found in volcanic geodes or as nodules in arid limestone environments.