Mineral

Botryoidal Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5–7 on Mohs scale; Color: Milky white, translucent; Luster: Waxy to vitreous; Crystal structure: Trigonal/Monoclinic (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6–2.7.

Hardness: 6
Color: Milky white, translucent
Luster: Waxy to vitreous

Identified June 20, 2026More mineral →

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Physical properties

Hardness: 6.5–7 on Mohs scale; Color: Milky white, translucent; Luster: Waxy to vitreous; Crystal structure: Trigonal/Monoclinic (cryptocrystalline); Cleavage: None; Specific Gravity: 2.6–2.7.

Formation & geological history

Formed through the low-temperature deposition of silica-rich fluids in cavities of volcanic or sedimentary rocks. The 'botryoidal' (grape-like) texture forms as mineral layers precipitate around a central nucleus.

Uses & applications

Used primarily as decorative specimens for collectors, in lapidary work for cabochons, and as a component in jewelry. It is also a source of industrial silica in large quantities.

Geological facts

This specimen displays a classic botryoidal habit, which means 'cluster of grapes' in Greek. chalcedony is actually composed of micro-fibrous growths of quartz and moganite.

Field identification & locations

Identify by its waxy luster, rounded bubble-like surfaces, and hardness (will scratch glass but cannot be scratched by a steel knife). Commonly found in volcanic regions of Brazil, Uruguay, and the US Northwest.