mineral

Chalcedony (Agate/Carnelian variant)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Translucent white to honey-yellow/orange; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline (trigonal/monoclinic); Cleavage: None; Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Translucent white to honey-yellow/orange
Luster: Waxy to vitreous

Identified June 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich water in cavities of volcanic rocks or sedimentary environments. It can form as geodes or nodules and is found in geological layers ranging from modern to hundreds of millions of years old.

Uses & applications

Commonly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a collector's specimen. Historically used for making seals and tools because of its durability.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen with a standard microscope. The varying colors are often due to trace impurities of iron or other minerals.

Field identification & locations

Identify in the field by its waxy luster, conchoidal fracture (curved breaks like glass), and lack of visible crystals. It is frequently found on beaches or in dry riverbeds as water-worn pebbles.

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