mineral

Chalcedony

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: waxy translucent greyish-white to tan; Luster: waxy to vitreous; Crystal structure: Trigonal/Monoclinic; Specific gravity: 2.6-2.64

Hardness: 6
Color: waxy translucent greyish-white to tan
Luster: waxy to vitreous

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: waxy translucent greyish-white to tan; Luster: waxy to vitreous; Crystal structure: Trigonal/Monoclinic; Specific gravity: 2.6-2.64

Formation & geological history

Secondary formation through the deposition of silica from aqueous solutions in volcanic and sedimentary environments, often filling nodules, cavities, or fractures.

Uses & applications

Commonly used in jewelry as cabochons, for ornamental carvings, and historically for stone tools and seals due to its toughness and fracture properties.

Geological facts

Chalcedony has been a prized gemstone since antiquity, notably used in ancient Mediterranean civilizations for cylinder seals and amulets.

Field identification & locations

Identify by its waxy luster, translucency, and conchoidal fracture. Often found along riverbeds or in volcanic outcrop areas like Oregon, Brazil, and India.