Sedimentary/Igneous (depending on host rock)
Geode with Quartz Crystals
SiO2 (Silicon Dioxide) in a geode formation
AI-generated identification · may be incorrectHardness: 7 (Quartz); Color: Clear, white, grey; Luster: Vitreous (glassy) inside, dull outside; Crystal structure: Trigonal (Quartz).
- Hardness
- 7 (Quartz)
- Color
- Clear, white, grey
- Luster
- Vitreous (glassy) inside, dull outside
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Physical properties
Hardness: 7 (Quartz); Color: Clear, white, grey; Luster: Vitreous (glassy) inside, dull outside; Crystal structure: Trigonal (Quartz).
Formation & geological history
Formed in cavities in sedimentary or igneous rocks, where mineral-rich water deposits layers of silica (often chalcedony or agate) and inward-growing crystals over thousands to millions of years.
Uses & applications
Commonly collected for aesthetic value, used in jewelry making, or as decorative display pieces.
Geological facts
Geodes are often hollow, but some are completely filled with crystals (called nodules). The word 'geode' comes from the Greek word 'geodes', meaning 'earthlike'.
Field identification & locations
Identified by a rough, relatively unremarkable exterior and a hollow interior lined with crystals. Often found in limestone deposits or volcanic ash beds.
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