metamorphic
Quartzite
Quartzite (composed primarily of SiO2)
Hardness: 7 on Mohs scale; Color: white to light pink/tan; Luster: vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: none, breaks with conchoidal fracture; Specific gravity: 2.63-2.65.
- Hardness
- 7 on Mohs scale
- Color
- white to light pink/tan
- Luster
- vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: white to light pink/tan; Luster: vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: none, breaks with conchoidal fracture; Specific gravity: 2.63-2.65.
Formation & geological history
Formed when quartz-rich sandstone is subjected to high heat and pressure during regional metamorphism, causing the quartz grains to recrystallize and fuse together into a dense, interlocking matrix.
Uses & applications
Used extensively in road construction as crushed stone, as railway ballast, for flooring, wall coverings, and high-end kitchen countertops.
Geological facts
Quartzite is so hard and dense that when struck, it will break through the quartz grains rather than around them, which distinguishes it from sandstone. Some pink varieties are often mistaken for Rose Quartz.
Field identification & locations
Identify by its extreme hardness (scratches glass easily) and granular, 'sugary' appearance on fresh surfaces. Commonly found in folded mountain belts and ancient shield areas globally.
