metamorphic
Quartzite Pebble
Quartzite (mostly SiO2)
Hardness: 7 on Mohs scale; Color: light brown, tan, and reddish-orange (due to iron oxide); Luster: dull to vitreous; Crystal structure: granular/interlocking; Cleavage: none.
- Hardness
- 7 on Mohs scale
- Color
- light brown, tan, and reddish-orange (due to iron oxide)
- Luster
- dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: light brown, tan, and reddish-orange (due to iron oxide); Luster: dull to vitreous; Crystal structure: granular/interlocking; Cleavage: none.
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure. This specimen shows significant rounding and smoothing consistent with fluvial (river) or glacial transport processes.
Uses & applications
Commonly used as construction aggregate, road ballast, decorative landscaping stone, and in glass manufacturing if high purity.
Geological facts
Quartzite is so hard and tough that it often outlasts the surrounding rocks during erosion, remaining as rounded pebbles in stream beds millions of years after the source rock has worn away.
Field identification & locations
Identify by its inability to be scratched by a steel knife and its grainy 'sugary' texture on fresh breaks. Found globally in riverbeds, beaches, and glacial till.
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