mineral

Quartz Geode

Crystalline Quartz (Silicon Dioxide, SiO2)

7.0 on Mohs scale; white to translucent light gray; vitreous luster; hexagonal crystal system (macro-crystalline in center); no cleavage; specific gravity 2.65.

Identified May 23, 2026More mineral →

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Physical properties

7.0 on Mohs scale; white to translucent light gray; vitreous luster; hexagonal crystal system (macro-crystalline in center); no cleavage; specific gravity 2.65.

Formation & geological history

Formed via secondary precipitation within cavities of volcanic or sedimentary rocks. Over millions of years, silica-rich mineral fluids seep into gas bubbles (vesicles) and crystallize inward.

Uses & applications

Commonly used for educational tools, decorative ornaments, crystal healing, and as a popular entry-level collector's specimen.

Geological facts

Geodes can range from less than an inch to several meters in size. Despite their often plain exterior, the hollow interior can contain a variety of beautiful mineral crystals including amethyst, citrine, or calcite.

Field identification & locations

Identified by a lumpy, cauliflower-like exterior and a hollow interior when cracked open. Found worldwide, with major deposits in Brazil, Uruguay, and the Midwestern United States (e.g., Keokuk geodes).

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