sedimentary
Quartz Geode
Silicon Dioxide (SiO2) in a sedimentary host
Hardness: 7 (crystals); Color: White to translucent; Luster: Vitreous/glassy inner crystals with a dull, earthy chalcedony or limestone rinded exterior; Crystal structure: Trigonal; Cleavage: None
- Hardness
- 7 (crystals)
- Color
- White to translucent
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Physical properties
Hardness: 7 (crystals); Color: White to translucent; Luster: Vitreous/glassy inner crystals with a dull, earthy chalcedony or limestone rinded exterior; Crystal structure: Trigonal; Cleavage: None
Formation & geological history
Formed in cavities within sedimentary rocks or volcanic ash. Minerals precipitate from groundwater over millions of years to form the crystal lining.
Uses & applications
Commonly used for geological education, tabletop decor, metaphysical energy collecting, and as a popular entry-level mineral specimen for collectors.
Geological facts
Geodes are essentially 'hollow rocks' that can take thousands of years to grow. While the outside looks like a common stone, the interior can hold surprises like amethyst, calcite, or celestite.
Field identification & locations
Identify in the field by looking for potato-shaped or rounded nodules that feel lighter than typical rocks of the same size. Typically found in limestone-rich deserts or volcanic ash beds.
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