mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Clear to white (milky); Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Clear to white (milky)
Luster: Vitreous (glassy)

Identified June 25, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Clear to white (milky); Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed when mineral-rich hydrothermal fluids seep into cavities in volcanic or sedimentary rock layers. Over long periods, crystals grow inward from the cavity walls. Found in environments spanning Jurassic to Cenozoic eras.

Uses & applications

Decorative display, metaphysical use, jewelry making, and lapidary art. High-quality quartz is also used in electronics and watchmaking for its piezoelectric properties.

Geological facts

The word 'geode' comes from the Greek word 'Geoides' meaning earth-like. No two geodes are exactly alike internally, and they can range from the size of a marble to several meters long.

Field identification & locations

Identified in the field by their rounded, lumpy, 'cauliflower-like' exterior which feels lighter than solid rocks of the same size. Commonly found in deserts or volcanic ash beds. Look for hollow sounds when tapped gently.