mineral

Quartz Geode

Crystalline Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Clear to milky white; Luster: Vitreous/Glassy; Crystal Structure: Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Clear to milky white
Luster: Vitreous/Glassy

Identified June 28, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Clear to milky white; Luster: Vitreous/Glassy; Crystal Structure: Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65.

Formation & geological history

Formed within cavities of volcanic or sedimentary rocks. Over time, mineral-rich water seeps into hollow spaces, depositing microcrystalline layers of chalcedony and larger quartz crystals as the solution cools and evaporates.

Uses & applications

Used primarily for ornamental decoration, metaphysical practice, jewelry components (druzies), and as a teaching tool for geology students and collectors.

Geological facts

Geodes appear like ordinary, lumpy rocks on the outside but contain hollow sparkly centers. The word 'geode' comes from the Greek word 'Geoides' meaning earth-like.

Field identification & locations

Identify in the field by looking for round, bumpy nodules that feel lighter than they look (indicating a hollow center). Common locations include Iowa (Keokuk), Mexico, and Brazil.