metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: White to light grey with translucent areas; Luster: Vitreous to waxy; Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- White to light grey with translucent areas
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: White to light grey with translucent areas; Luster: Vitreous to waxy; Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz sandstone under intense heat and pressure, typically during mountain-building events. These smoothed pebbles are the result of river or beach erosion over thousands to millions of years.
Uses & applications
Used as decorative landscaping stones, raw material for glass manufacturing, high-quality construction aggregate, and occasionally for primitive tool-making due to its hardness.
Geological facts
Quartzite is so tough that it often outlasts the mountains it was formed in, becoming the primary component of river gravel. It is often confused with marble, but unlike marble, it will not fizz when exposed to acid and cannot be scratched by a steel blade.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its slightly sugary or crystalline appearance when viewed closely. Common in glacial till, riverbeds, and coastal beaches globally.
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