mineral
Quartz Crystal (Geode Fragment)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale. Color: White to translucent clear with grey/brownish exterior rind. Luster: Vitreous (glass-like) on fresh crystalline surfaces. Crystal structure: Hexagonal/trigonal. Cleavage: None (conchoidal fracture). Specific gravity: ~2.65.
- Hardness
- 7 on Mohs scale
- Color
- White to translucent clear with grey/brownish exterior rind
- Luster
- Vitreous (glass-like) on fresh crystalline surfaces
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Physical properties
Hardness: 7 on Mohs scale. Color: White to translucent clear with grey/brownish exterior rind. Luster: Vitreous (glass-like) on fresh crystalline surfaces. Crystal structure: Hexagonal/trigonal. Cleavage: None (conchoidal fracture). Specific gravity: ~2.65.
Formation & geological history
Formed in cavities (geodes or veins) within igneous or sedimentary rocks through precipitation of silica-rich hydrothermal fluids over thousands to millions of years.
Uses & applications
Commonly collected as mineral specimens, used in lapidary work, jewelry, crystal healing practices, and industrially for electronics and optics when pure.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Geode fragments like this often display sparkling interior micro-crystals (drusy quartz) protected by a weathered basaltic or limestone host outer shell.
Field identification & locations
Identified in the field by its hardness (scratches glass), glass-like luster, uneven or conchoidal fracture, and lack of reaction to cold dilute acid. Commonly found worldwide in volcanic zones, gravel beds, and stream deposits.
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