metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-white with subtle banding; Luster: Dull to vitreous; Structure: Granoblastic (interlocking quartz grains); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with subtle banding
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-white with subtle banding; Luster: Dull to vitreous; Structure: Granoblastic (interlocking quartz grains); Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. This specimen has been rounded by fluvial or glacial erosion.
Uses & applications
Commonly used in construction as railway ballast, road aggregate, and in landscaping. Pure quartzite is used to produce silica sand for glass manufacturing.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, remaining as rounded pebbles in riverbeds or forming prominent ridges on mountain peaks.
Field identification & locations
Identify by its extreme hardness (it will easily scratch glass) and its sugary, granular texture. Commonly found in riverbeds, glacial tills, and ancient mountain belts.
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