metamorphic
Quartzite pebble
Quartzite (SiO2)
Hardness: 7 (Mohs scale); Color: Tan, beige, white, and translucent gray; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 - 2.8.
- Hardness
- 7 (Mohs scale)
- Color
- Tan, beige, white, and translucent gray
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan, beige, white, and translucent gray; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 - 2.8.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific grain appears water-worn and rounded, suggesting it was transported in a river or glacial environment.
Uses & applications
Used in railway ballast, road construction, manufacturing of glass, and high-quality landscaping sand.
Geological facts
Quartzite is so durable that it often remains behind as hills or ridges when softer surrounding rock is eroded away. It is often mistake for marble, but unlike marble, it will not fizz in contact with acid.
Field identification & locations
Identify in the field by its inability to be scratched by steel and its grainy, sandpaper-like texture that still looks 'fused.' Found globally in ancient mountain belts and riverbeds.
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