mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: White, clear, or off-white; Luster: Vitreous (glassy); Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: White, clear, or off-white
Luster: Vitreous (glassy)

Identified May 13, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: White, clear, or off-white; Luster: Vitreous (glassy); Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Formed as hollow cavities in sedimentary or volcanic rock that are filled by the slow precipitation of mineral-rich groundwater over thousands of years.

Uses & applications

Primarily used for decorative display, crystal collecting, education, and sometimes in metaphysical practices. Industrial quartz is used in electronics and glass-making.

Geological facts

Geodes are often indistinguishable from ordinary rocks on the outside. They are uniquely defined by their hollow interior lined with inward-growing crystals.

Field identification & locations

Identify in the field by looking for rounded, lumpy stones that feel unusually lightweight for their size. Common in limestone deserts or volcanic ash beds. Look for a hard, silica-rich outer shell.