metamorphic
Quartzite
Silicon Dioxide (SiO2)
Hardness 7 on Mohs scale, vitreous to greasy luster, white to off-white with pinkish and greyish hues, granoblastic texture, no cleavage, specific gravity around 2.65
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Physical properties
Hardness 7 on Mohs scale, vitreous to greasy luster, white to off-white with pinkish and greyish hues, granoblastic texture, no cleavage, specific gravity around 2.65
Formation & geological history
Formed from the regional or contact metamorphism of quartz-rich sandstone under intense heat and pressure, causing the original quartz grains to recrystallize and fuse firmly together.
Uses & applications
Used as a crushed stone in road construction, railway ballast, aggregate in concrete, decorative stone, landscaping rock, and occasionally in glass making.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering. When struck with a hammer, quartzite fractures across quartz grains rather than along grain boundaries like sandstone.
Field identification & locations
Identified by its high hardness (scratches glass easily), interlocking quartz texture, and sugary appearance on fresh surfaces. Commonly found in mountainous regions, riverbeds, and glacial deposits worldwide.
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