metamorphic
Quartzite Geode or Crystalline Quartz Node
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Tan to milky white; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Tan to milky white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan to milky white; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65
Formation & geological history
Formed by the metamorphism of quartz-rich sandstone or through the deposition of silica-rich hydrothermal fluids in cavities within host rock. Often found in ancient riverbeds or sedimentary basins.
Uses & applications
Used largely for decorative landscaping, as a construction aggregate, or as a lapidary material for hobbyists.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. These specific rounded forms are often called 'river eggs' or 'potato stones' before they are cracked open to reveal internal crystals.
Field identification & locations
Identified by its extreme hardness (cannot be scratched by steel) and lack of visible mineral grains other than quartz. Commonly found in gravel pits or areas with high metamorphic activity.
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