metamorphic
Quartzite
Quartzite (SiO2)
Mohs hardness 7, white to light gray with reddish/yellowish iron oxide staining, vitreous to sugary luster, granoblastic texture, non-foliated, conchoidal to uneven fracture.
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Physical properties
Mohs hardness 7, white to light gray with reddish/yellowish iron oxide staining, vitreous to sugary luster, granoblastic texture, non-foliated, conchoidal to uneven fracture.
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone under intense heat and pressure, causing quartz grains to recrystallize and interlock tightly.
Uses & applications
Widely used as a decorative landscape boulder, dimension stone, building cladding, crushed stone for road construction, and ballast.
Geological facts
Quartzite is so hard and tough that when it breaks, it fractures through the quartz grains rather than along the boundaries between them, unlike sandstone.
Field identification & locations
Identified by its extreme hardness (scratches glass easily), interlocking sugary texture, and resistance to chemical weathering. Found globally in mountainous metamorphic terrains.
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