mineral

Quartz Geode

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale. Color: White to transparent, sometimes with yellowish or brownish tinges. Luster: Vitreous (glassy). Crystal structure: Trigonal. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Luster: Vitreous (glassy)

Identified August 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hollow cavities in rocks, most commonly in sedimentary limestone or volcanic basalt, through the slow precipitation of silica-rich groundwater over millions of years.

Uses & applications

Used in decorative items, lapidary art, crystal collections, and sometimes in electronic applications or glass-making depending on purity.

Geological facts

Geodes start as gas bubbles in volcanic rock or animal burrows/nodules in sedimentary layers. Over time, mineral-rich water seeps in and deposits crystals layer by layer, growing inward from the outer wall toward the center.

Field identification & locations

Easily identified by its rough outer rock shell enclosing a hollow cavity lined with sparkling quartz crystal points. Found worldwide, particularly in locations like Brazil, Mexico, and the USA (e.g., Keokuk, Iowa).