mineral

Blue Chalcedony

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Hardness: 6.5–7 on Mohs scale; Color: Translucent grayish-blue to lavender; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58–2.64

Hardness: 6
Color: Translucent grayish-blue to lavender
Luster: Waxy to vitreous

Identified April 12, 2026More mineral →

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Physical properties

Hardness: 6.5–7 on Mohs scale; Color: Translucent grayish-blue to lavender; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58–2.64

Formation & geological history

Formed from the deposition of silica-rich fluids in cavities or fractures of volcanic or sedimentary rocks at relatively low temperatures. Often found in geodes or as botryoidal masses in basaltic rock.

Uses & applications

Predominantly used as a gemstone for jewelry (cabochons, beads), ornamental carvings, and by collectors for its aesthetic waxy translucent appearance.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are so small they can only be seen under extreme magnification. It has been used since the Bronze Age for seals and amulets.

Field identification & locations

Identify in the field by its waxy luster, conchoidal fracture (curved glass-like breaks), and lack of visible crystals. It is commonly found in areas of volcanic activity like Oregon, Turkey, and Namibia.

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