mineral

Quartz Geode

Silicon Dioxide (SiO2) - Crystalline Quartz

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: White to translucent tan with brownish outer rind; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: White to translucent tan with brownish outer rind
Luster: Vitreous to dull

Identified May 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed as secondary minerals in hollow cavities (vugs) within igneous or sedimentary rocks. Silica-rich groundwater precipitates crystals over thousands of years.

Uses & applications

Primarily used as decorative specimens, for educational purposes, in rock collections, and occasionally as minor semi-precious gemstones.

Geological facts

Geodes are virtually indestructible by weather because the silica outer shell is much harder than the host rock that once surrounded them; they are often found as loose nodules in stream beds or desert soil.

Field identification & locations

Identify by its rounded, cauliflower-like exterior texture and internal crystal growth. Commonly found in limestone or volcanic ash beds in regions like the American Midwest or Brazil.