mineral

Botryoidal Chalcedony

Cryptocrystalline Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Tan, brownish-orange, waxy luster; Crystal Structure: Trigonal/Monoclinic (microscopic); Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.6-2.64

Hardness: 6
Color: Tan, brownish-orange, waxy luster

Identified June 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Tan, brownish-orange, waxy luster; Crystal Structure: Trigonal/Monoclinic (microscopic); Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.6-2.64

Formation & geological history

Formed via precipitation of silica-rich fluids in cavities within volcanic or sedimentary rocks. The botryoidal (grape-like) texture occurs as silica layers grow slowly around multiple nucleation points. Depending on location, these can range from modern era to hundreds of millions of years old.

Uses & applications

Widely used for ornamental carvings, semi-precious jewelry (lapidary), and as aggregate in some industrial applications. Highly valued by amateur rockhounds and mineral collectors for its unique textures.

Geological facts

The term 'botryoidal' is derived from the Greek word 'botrys', meaning 'bunch of grapes'. Chalcedony is the umbrella term for several quartz varieties including agate, jasper, and carnelian.

Field identification & locations

Identify by its waxy luster, rounded 'bubble' surface texture, and hardness (it will scratch glass). Commonly found in dry regions, volcanic ash beds, and river gravels. Notable locations include Oregon, Arizona, Brazil, and India.

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