metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 on Mohs scale; Color: Off-white to light gray with dark inclusions; Luster: Vitreous to waxy; Structure: Granular/Crystalline; Cleavage: None; Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Off-white to light gray with dark inclusions
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Off-white to light gray with dark inclusions; Luster: Vitreous to waxy; Structure: Granular/Crystalline; Cleavage: None; Specific Gravity: 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen has been rounded by fluvial (river) or glacial erosion.
Uses & applications
Raw quartzite is used in construction, road ballast, and as a source of silica for glass manufacturing. Smooth pebbles are popular for landscaping and aquarium decor.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks in a landscape, forming resistant ridges. It is often confused with marble, but quartzite will scratch glass and won't fizz in acid.
Field identification & locations
Identify by its extreme hardness and granular texture. Look for it in riverbeds, glacial tills, or mountain outcrops. For collectors, look for unique colors or translucent qualities.
