mineral
Quartz Geode
Silicon Dioxide (SiO2) - Crystalline Quartz
AI-generated identification · may be incorrectHardness: 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 More mineral →
Explore Quartz Geode in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
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
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.
