metamorphic
Quartzite
Quartzite (SiO2-rich metamorphic rock)
AI-generated identification · may be incorrectHardness 7 on Mohs scale, vitreous to dull luster, granoblastic/interlocking crystalline texture, non-foliated, colors range from light gray, white, tan, to pale yellow-orange from iron oxide weathering.
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Physical properties
Hardness 7 on Mohs scale, vitreous to dull luster, granoblastic/interlocking crystalline texture, non-foliated, colors range from light gray, white, tan, to pale yellow-orange from iron oxide weathering.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone under extreme heat and pressure, causing quartz grains to recrystallize into a dense interlocking network.
Uses & applications
Used as crushed stone in construction, road aggregate, ballast, decorative landscaping stone, and historically as a source of silica in glassmaking.
Geological facts
Quartzite is so tough that when it breaks, it fractures across the individual quartz grains rather than along the grain boundaries, unlike sandstone.
Field identification & locations
Identified in the field by its hardness (scratches glass and steel effortlessly) and granular, sugary appearance. Extremely widespread in ancient mountain belts and glaciated regions.
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