metamorphic

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, with minor feldspar or mica

AI-generated identification · may be incorrect

Hardness about 7 Mohs; pale gray-white, granular, and vitreous to sugary luster. Interlocking quartz crystals show no obvious cleavage and typically have specific gravity near 2.65; the rough surface and lighting limit certainty.

Identified September 16, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism, commonly during mountain-building events. Its precise geological age cannot be determined from the photograph.

Uses & applications

Used as crushed stone, aggregate, road material, building stone, and decorative slabs; attractive pieces may be collected, though this specimen appears ordinary.

Geological facts

Quartzite is generally harder and more resistant to weathering than its sandstone precursor. A useful test is that a steel file usually fails to scratch fresh quartzite, while quartz-rich sandstone may crumble around individual grains.

Field identification & locations

Common in metamorphic mountain belts worldwide, including the Appalachians, Rocky Mountains, Alps, and India. Look for fused quartz grains, a sugary texture, and fracture through grains rather than around them; acid should not fizz unless carbonate minerals are present.