metamorphic
Quartzite
Quartzite (chiefly SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray, but often reddish or pink due to iron oxides; Luster: vitreous to dull; Structure: granoblastic/non-foliated; Cleavage: none (fractures conchoidally)
- Hardness
- 7 on Mohs scale
- Luster
- vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white to gray, but often reddish or pink due to iron oxides; Luster: vitreous to dull; Structure: granoblastic/non-foliated; Cleavage: none (fractures conchoidally)
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, eliminating pore spaces.
Uses & applications
Used in construction as crushed stone for road ballast, floor tiles, and countertop surfaces. Sometimes used as a decorative stone in landscaping.
Geological facts
Quartzite is so hard and durable that it often forms the crests of mountain ranges because it resists weathering better than surrounding rocks. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify it by its extreme hardness and sugary, crystalline texture. Unlike sandstone, which breaks around the grains, quartzite breaks through the grains. It is found globally in mountainous regions and ancient metamorphic shields.
