metamorphic
River Quartz / Quartzite Pebbles
Quartzite (primarily Silicon Dioxide, SiO2)
Hardness: 7 on Mohs scale. Color: white to reddish-orange. Luster: dull to vitreous when wet. Crystal structure: trigonal. Cleavage: none. Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- white to reddish-orange
- Luster
- dull to vitreous when wet
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Physical properties
Hardness: 7 on Mohs scale. Color: white to reddish-orange. Luster: dull to vitreous when wet. Crystal structure: trigonal. Cleavage: none. Specific gravity: 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. These specimens have been rounded and smoothed by fluvial (river) erosion over many years.
Uses & applications
Commonly used in landscaping, as decorative gravel, in construction as aggregate, and sometimes in aquariums.
Geological facts
Quartzite is harder and more durable than the parent sandstone. The reddish hue in some specimens is typically caused by trace amounts of iron oxide (hematite).
Field identification & locations
Identify by its hardness (will scratch glass) and lack of reaction to acid. Commonly found in riverbeds, glacial deposits, and beaches.
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