mineral

Chalcedony (Quartz)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Waxy white to honey-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal/Monoclinic (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.6-2.64

Hardness: 6
Color: Waxy white to honey-brown
Luster: Vitreous to waxy

Identified June 25, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Waxy white to honey-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal/Monoclinic (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.6-2.64

Formation & geological history

Formed through the deposition of silica from water in cavities, volcanic rocks, and sedimentary layers at relatively low temperatures.

Uses & applications

Used in gemstone jewelry, semi-precious ornamental carvings, historical seals, and as industrial abrasives due to its hardness.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen without high magnification. It has been used since the Bronze Age for making cylinder seals.

Field identification & locations

Identify by its waxy luster, conchoidal fracture (curved breaks), and inability to be scratched by a steel knife. Commonly found in riverbeds and volcanic regions worldwide.