mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness of 7 on the Mohs scale, transparent to translucent with vitreous to sub-vitreous luster, trigonal crystal system with distinct crystal points lining the cavity, and no distinct cleavage.

Identified August 6, 2026More mineral →

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Physical properties

Hardness of 7 on the Mohs scale, transparent to translucent with vitreous to sub-vitreous luster, trigonal crystal system with distinct crystal points lining the cavity, and no distinct cleavage.

Formation & geological history

Formed in hollow spaces in sedimentary or volcanic rocks where silica-rich groundwater percolates and slowly precipitates crystals along the cavity walls over millions of years.

Uses & applications

Commonly used in decorative ornamental pieces, jewelry, metaphysical practices, and as popular specimens for rock and mineral collections.

Geological facts

Geodes start as hollow nodules or bubbles in rock. Over long periods, mineral-rich water deposits microscopic crystals that eventually grow into the sparkling quartz points seen inside the cavity.

Field identification & locations

Easily identified by their rounded, weathered exterior and hollow interior lined with sparkling crystals. Found worldwide, particularly in regions with limestone deposits or volcanic activity such as in Mexico, Brazil, and the US (e.g., Iowa and Indiana).