metamorphic
Quartzite pebble
Quartzite (SiO2 silicon dioxide)
Hardness: 7 Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); specific gravity: 2.63–2.65
- Hardness
- 7 Mohs scale
- Color
- white to light gray
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); specific gravity: 2.63–2.65
Formation & geological history
Quartzite forms when quartz-rich sandstone is subjected to high heat and pressure during regional metamorphism, causing the sand grains to recrystallize into a dense interlocking matrix.
Uses & applications
Used extensively in road construction, as railroad ballast, in the production of glass, and occasionally as a decorative landscaping stone.
Geological facts
Quartzite is one of the most durable and physically resistant rocks on Earth's surface. It can be harder than the steel blade of a knife.
Field identification & locations
Identify in the field by its grainy, sugar-like texture and its inability to be scratched by steel. It breaks across grains rather than around them, unlike its parent sandstone.
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