mineral

Botryoidal Chalcedony (Agate/Carnelian)

Chalcedony (SiO2)

Hardness: 6.5–7 (Mohs scale); Color: Translucent orange to tan; Luster: Waxy to vitreous; Structure: Microcrystalline (Cryptocrystalline) quartz; Habit: Botryoidal (grape-like orbicular masses); Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Translucent orange to tan
Luster: Waxy to vitreous

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the low-temperature deposition of silica from groundwater into cavities, fissures, or volcanic bubbles (vesicles). This specimen displays secondary iron-oxide staining, giving it the carnelian-like orange tint.

Uses & applications

Used primarily for lapidary work, jewelry (cabochons), and as display specimens for mineral collectors. Some cultures use it for ornamental carvings or protective amulets.

Geological facts

The term 'botryoidal' comes from the Greek word 'botrys', meaning a bunch of grapes. While chemically identical to quartz, chalcedony is composed of microscopic fibers of quartz and moganite intergrown.

Field identification & locations

Identify in the field by its waxy texture, lack of visible crystals, and distinctive bubbly or 'melted candle wax' appearance. Commonly found in desert regions, gravel beds, or weathered volcanic ash deposits. Collectors look for high translucency and unbroken 'bubbles'.

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