mineral
Quartz Geode
Silicon Dioxide (SiO2) within Sedimentary or Igneous host
Hardness: 7 (Mohs scale); Color: Tan/brown exterior with white/clear crystalline interior; Luster: Dull/earthy exterior, vitreous (glassy) interior; Crystal Structure: Trigonal; Cleavage: None/Conchoidal fracture.
- Hardness
- 7 (Mohs scale)
- Color
- Tan/brown exterior with white/clear crystalline interior
- Luster
- Dull/earthy exterior, vitreous (glassy) interior
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan/brown exterior with white/clear crystalline interior; Luster: Dull/earthy exterior, vitreous (glassy) interior; Crystal Structure: Trigonal; Cleavage: None/Conchoidal fracture.
Formation & geological history
Formed through the precipitation of minerals from hydrothermal fluids or groundwater within cavities (bubbles) in volcanic rock or sedimentary limestone over millions of years.
Uses & applications
Primarily used as decorative display pieces, educational specimens, and in crystal healing practices. Larger, high-quality geodes may be cut for jewelry or high-end decor.
Geological facts
The word geode comes from the Greek word 'Geoides' which means 'earth-like'. Despite their plain exterior, they contain hollow cavities lined with crystals. This specimen appears to be a small quartz geode, likely from a sedimentary environment.
Field identification & locations
Identify in the field by looking for rounded, lumpy nodules that feel unusually light for their size, suggesting a hollow center. Common in desert regions of the US, Brazil, and Mexico. Collectors look for unbroken nodules to crack open themselves.
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