mineral
Quartz Geode (Cracked)
Crystalline Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: white to translucent; Luster: vitreous (glassy) to dull; Crystal structure: hexagonal/trigonal; Cleavage: none (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- white to translucent
- Luster
- vitreous (glassy) to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: white to translucent; Luster: vitreous (glassy) to dull; Crystal structure: hexagonal/trigonal; Cleavage: none (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed primarily as secondary hydrothermal deposits filling cavities (vugs) in volcanic or sedimentary rocks. Over millions of years, mineral-rich groundwater seeps into these cavities, slowly precipitating silica which crystallizes into quartz.
Uses & applications
Commonly used for educational purposes, museum and private collections, decorative home decor, and sometimes in New Age practices as healing crystals. High-purity quartz is used in electronics and glass-making.
Geological facts
Geodes often look like ordinary, bumpy rocks from the outside; their inner crystalline wonder is only revealed when cracked open. Some geodes can contain amethyst, citrine, or chalcedony instead of common white quartz.
Field identification & locations
Identify in the field by looking for round, bumpy, or nodules of rock that feel lighter than they look (indicating a hollow center). Commonly found in desert regions of the US, Brazil, and Uruguay.
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