mineral

Chalcedony on Matrix

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: waxy translucent white to tan on white opaque matrix; Luster: waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: none; Fracture: conchoidal.

Hardness: 6
Color: waxy translucent white to tan on white opaque matrix
Luster: waxy to vitreous

Identified May 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich fluids in volcanic cavities, sedimentary basins, or as replacement material. Typically found in Cenozoic era formations.

Uses & applications

Used in gemstone carvings, jewelry (cabochons), and for healing crystals or as a decorative collector specimen.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are so small they can only be seen under extreme magnification. Agate and Jasper are both varieties of chalcedony.

Field identification & locations

Identify by its waxy luster and the way it often forms botryoidal (grape-like) or smooth coatings over a host rock. Commonly found in desert environments like Arizona or Oregon.