mineral

Chalcedony (Botryoidal)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs), Color: White/Grey, Luster: Waxy to Vitrous, Crystal Structure: Hexagonal (Trigonal) - Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.6-2.64.

Hardness: 6

Identified June 1, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs), Color: White/Grey, Luster: Waxy to Vitrous, Crystal Structure: Hexagonal (Trigonal) - Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.6-2.64.

Formation & geological history

Formed from the precipitation of silica-rich groundwater in cavities of volcanic and sedimentary rocks. Typically occurs as a secondary mineral in geodes or as a replacement mineral.

Uses & applications

Used primarily in lapidary arts, jewelry (cabochons), and for ornamental carvings. Industrial uses include use as an abrasive in specific polishing processes.

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen under a normal microscope. The 'bumpy' texture seen on this specimen is known as a botryoidal (grape-like) growth habit.

Field identification & locations

Identify in the field by its waxy luster, hardness (it will scratch glass), and its distinctive mammillary or botryoidal surface texture. Commonly found in desert regions or volcanic areas.