mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: white/colorless; Luster: vitreous (glassy); Crystal structure: trigonal; Cleavage: none/conchoidal fracture; Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: white/colorless
Luster: vitreous (glassy)

Identified June 21, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: white/colorless; Luster: vitreous (glassy); Crystal structure: trigonal; Cleavage: none/conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Formed as mineral-rich water precipitates within hollow cavities of sedimentary rocks or volcanic bubbles. These can date back millions of years depending on the host rock formation.

Uses & applications

Primarily used for geological education, home decoration, and metaphysical/gemstone collecting. Also used in small-scale jewelry.

Geological facts

The word geode comes from the Greek word 'Geoides' meaning earth-like. They appear as unremarkable round rocks on the outside but contain sparkling crystal interiors.

Field identification & locations

Identify in the field by looking for round or egg-shaped nodules that feel lighter than they look (indicating a hollow center). Common in areas with limestone or basalt outcrops. Often found in abundance in places like Iowa, USA or Brazil.