metamorphic
Quartzite
Metamorphosed Sandstone (primarily SiO2)
Hardness: 7 (Mohs scale), Color: White to light gray with slight green tint, Luster: Dull to vitreous, Crystal structure: Granular/Massive, Cleavage: None (breaks with conchoidal or uneven fracture), Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: White to light gray with slight green tint, Luster: Dull to vitreous, Crystal structure: Granular/Massive, Cleavage: None (breaks with conchoidal or uneven fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of pure quartz sandstone under intense heat and pressure. The original quartz grains recrystallize into an interlocking mosaic.
Uses & applications
Used as a decorative stone in landscaping, as a construction aggregate, for railroad ballast, and in the manufacturing of glass and ceramics.
Geological facts
Quartzite is so hard that it will scratch glass and even steel. It is one of the most durable rocks on the Earth's surface and often forms the peaks of mountains because it resists weathering so well.
Field identification & locations
Identify in the field by its grainy, sugary texture and extreme hardness. It is commonly found in fold mountain belts throughout the world, such as the Appalachians or the Alps.
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