metamorphic
Quartzite (River Pebble)
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, off-white, or brownish-grey; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan, off-white, or brownish-grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, off-white, or brownish-grey; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. This specimen has been rounded by fluvial (river) erosion.
Uses & applications
Used in construction as crushed stone for road base, railway ballast, and occasionally as decorative landscaping stones or tumbling material.
Geological facts
Quartzite is so durable that it can withstand millions of years of river erosion and chemical weathering. It is much harder and more resistant than the sandstone from which it originated.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and granular, sugary appearance on a broken face. Commonly found in riverbeds and glacial deposits.
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