metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale); Color: White, gray, or pinkish; Luster: Vitreous to dull; Crystal structure: Trigonal (granular); Cleavage: None; Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- White, gray, or pinkish
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 (Mohs scale); Color: White, gray, or pinkish; Luster: Vitreous to dull; Crystal structure: Trigonal (granular); Cleavage: None; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, causing quartz grains to recrystallize into a dense, interlocking mosaic. Most common in mountain belts and ancient cratons.
Uses & applications
Used as crushed stone for road construction and railway ballast; frequently used in high-end countertops, flooring, and as a decorative stone in landscaping.
Geological facts
Quartzite is so hard that it will scratch glass and steel. In the field, it is distinguished from sandstone because it breaks through the quartz grains rather than around them.
Field identification & locations
Identify by its sugary texture and extreme hardness. It won't fizz with acid (distinguishing it from marble) and is found globally in regions with folded mountain ranges.
