metamorphic
Quartz-rich rock, likely quartzite
Quartzite; predominantly crystalline silicon dioxide (SiO₂)
AI-generated identification · may be incorrectWhite to pale gray, granular and massive with a subtle sugary texture; vitreous to dull luster. Quartz hardness is about 7 Mohs, with no cleavage and irregular fracture; exact identification is limited by the image.
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Physical properties
White to pale gray, granular and massive with a subtle sugary texture; vitreous to dull luster. Quartz hardness is about 7 Mohs, with no cleavage and irregular fracture; exact identification is limited by the image.
Formation & geological history
Forms when quartz-rich sandstone is recrystallized under heat and pressure during metamorphism, commonly from Precambrian to younger mountain-building events. It occurs in metamorphic belts and resistant ridges worldwide.
Uses & applications
Used as crushed stone, aggregate, dimension stone, countertops, and decorative material; attractive pieces may be collected but are not generally gemstone grade.
Geological facts
Quartzite is typically tougher and more recrystallized than sandstone, and individual sand grains may be difficult to see. Acid generally produces no reaction, helping distinguish it from calcite-rich marble or limestone.
Field identification & locations
Look for a hard, nonporous pale rock that scratches glass and breaks through grains rather than around them; a steel nail should not scratch it. Common sources include India, Brazil, the United States, Canada, and mountain regions globally.
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