mineral

Botryoidal Chalcedony (Quartz Var.)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: White to pale tan/beige, Luster: Waxy to vitreous (glassy), Crystal Structure: Trigonal/Microcrystalline, Specific Gravity: 2.6-2.65, Texture: Botryoidal (grape-like clusters)

Hardness: 6

Identified July 3, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the precipitation of silica from low-temperature hydrothermal fluids or groundwater in volcanic cavities, sedimentary rocks, or fossil replacement. This specific specimen shows characteristic mammillary growth patterns found in many desert environments.

Uses & applications

Primarily used as a collector specimen, for lapidary work (carvings and cabochons), and in alternative medicine/metaphysical practices. Varieties of chalcedony are also used for high-precision bearings and mortars.

Geological facts

This specimen displays a 'botryoidal' habit, a name derived from the Greek word 'botrys', meaning a bunch of grapes. Chalcedony is technically a fibrous variety of quartz where the fibers are so small they are invisible under a standard microscope.

Field identification & locations

Identify in the field by its hardness (will scratch glass), waxy luster, and lack of visible cleavage. Commonly found in areas with past volcanic activity or in limestone deposits. Look for it in the desert regions of the SW United States, Morocco, and India.

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