mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Clear to white or translucent. Luster: Vitreous (glassy). Crystal Structure: Trigonal/Hexagonal quartz crystals lining a hollow cavity. Cleavage: None, exhibits conchoidal fracture.

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

Identified July 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities within volcanic rocks or sedimentary deposits where silica-rich groundwater gradually precipitates quartz crystals over millions of years.

Uses & applications

Used in ornamental pieces, lapidary art, crystal display specimens, educational collections, and jewelry.

Geological facts

Geodes often look like ordinary, unremarkable rounded rocks on the outside, but contain brilliant crystal cavities when cracked or sliced open.

Field identification & locations

Identified by a rough exterior shell surrounding a hollow central cavity filled with sparkling, well-formed quartz crystals. Commonly found in regions with ancient volcanic activity such as Brazil, Uruguay, Morocco, and the Midwestern United States (e.g., Iowa).