metamorphic
Quartzite
Metamorphic Rock (composed mainly of SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, pink, or reddish-brown due to iron impurities; Luster: vitreous to dull; Crystal Structure: non-foliated, granular; very durable and weather-resistant.
- 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, gray, pink, or reddish-brown due to iron impurities; Luster: vitreous to dull; Crystal Structure: non-foliated, granular; very durable and weather-resistant.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone. High heat and pressure cause the individual quartz grains to recrystallize and fuse together. It can be found in mountain ranges and ancient continental shields.
Uses & applications
Used as crushed stone for road construction and railway ballast; due to its hardness and aesthetic, it is frequently used as kitchen countertops, flooring, and decorative building stone.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the crests of ridges and resistant hilltops. During the Stone Age, it was occasionally used as a substitute for flint to create tools, though it is more difficult to fracture predictably.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its sugary, granular appearance. Unlike sandstone, quartzite fractures across the original grains rather than around them. Found globally, especially in Precambrian shield areas.
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