mineral

Quartz (Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: translucent white to grayish, Luster: waxy to vitreous, Crystal System: Hexagonal (cryptocrystalline), Cleavage: None (conchoidal fracture)

Identified July 15, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: translucent white to grayish, Luster: waxy to vitreous, Crystal System: Hexagonal (cryptocrystalline), Cleavage: None (conchoidal fracture)

Formation & geological history

Formed from the deposition of silica-rich fluids in volcanic cavities or sedimentary environments at relatively low temperatures.

Uses & applications

Used in jewelry as gemstones, in decorative lapidary arts, and as a source of high-purity silica for industrial electronics and glass manufacturing.

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 and jewelry.

Field identification & locations

Look for a translucent, waxy appearance and a smooth, curved fracture surface (conchoidal). It is common in riverbeds, desert pavements, and volcanic regions globally.