mineral

Botryoidal Chalcedony (Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: White, cream, or light grey; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: White, cream, or light grey
Luster: Waxy to vitreous

Identified June 20, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: White, cream, or light grey; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed through the deposition of silica-rich groundwater in cavities or volcanic rock vesicles. The 'botryoidal' (grape-like) texture develops as layers of microcrystalline quartz grow outward from multiple nuclei.

Uses & applications

Commonly used as a decorative specimen for collectors, carved into ornaments, or tumbled into semi-precious gemstones for jewelry.

Geological facts

The term 'botryoidal' comes from the Greek word 'botrys', meaning a bunch of grapes. Chalcedony is composed of two different silica minerals: quartz and moganite.

Field identification & locations

Identify by its 'bubbly' surface texture and parallel banding seen on the sides. Found globally in volcanic regions; common locations include Brazil, India, and the Western United States.

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