Mineral (Primary constituent)
Quartz River Cobble
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Off-white/Milky; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline in this form); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Off-white/Milky
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Off-white/Milky; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline in this form); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed from hydrothermal veins or as a constituent in igneous/metamorphic rocks. This specific specimen has been shaped and smoothed by fluvial (river) erosion over thousands of years.
Uses & applications
Used conceptually in landscaping, as a source of high-purity silica for glassmaking, or as a decorative 'worry stone' or paperweight.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. This specimen is an example of 'massive quartz' rather than a distinct crystal point.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife (H=7). Look for the rounded, 'river-worn' texture and waxy surface on white or tan specimens.
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Potassium Aluminum Silicate (KAlSi3O8)
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Quartz
Silicon dioxide (SiO2)
Mineral