metamorphic
Quartzite Pebbles
Quartzite (SiO2 silicon dioxide dominant)
Hardness: 7 on Mohs scale; Color: Tan, brown, and grey; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular); Cleavage: None; Specific gravity: approx. 2.65
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, and grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, and grey; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular); Cleavage: None; Specific gravity: approx. 2.65
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone. Through heat and pressure, grain boundaries fuse into a solid mass. These specific specimens are water-worn 'river pebbles' shaped by fluvial erosion over thousands of years.
Uses & applications
Used primarily as construction aggregate, landscaping stones (river rock), and as decorative elements in aquariums or gardens. Polished versions are used in jewelry and crafts.
Geological facts
Quartzite is one of the most durable rocks on the Earth's surface. It is often mistake for marble, but unlike marble, quartzite will not fizz in contact with acid and is significantly harder than a steel blade.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sugary texture under a hand lens. Commonly found in riverbeds, glacial tills, and decorative gravel. For collectors, look for smoothness and unique color banding.
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