metamorphic
Quartz-rich rock, likely quartzite
Quartzite; predominantly crystalline SiO₂
AI-generated identification · may be incorrectWhite to light gray, sugary granular texture, vitreous to slightly pearly luster, and no obvious cleavage; quartz hardness is Mohs 7, with specific gravity about 2.65. The specimen may contain minor mica or feldspar, causing darker flecks.
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Physical properties
White to light gray, sugary granular texture, vitreous to slightly pearly luster, and no obvious cleavage; quartz hardness is Mohs 7, with specific gravity about 2.65. The specimen may contain minor mica or feldspar, causing darker flecks.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism, commonly during mountain building; its exact geological age cannot be determined from the photograph. It commonly occurs in metamorphic belts and resistant ridges.
Uses & applications
Used as crushed stone, aggregate, road material, slabs, and decorative stone; attractive pieces are collected but are generally low-value unless unusually pure or patterned.
Geological facts
Its interlocking quartz grains make it much harder and more durable than the original sandstone. The apparent sparkle is typical of many small quartz grains reflecting light.
Field identification & locations
Identify it by its granular quartz texture, lack of visible sand-layering, hardness sufficient to scratch glass, and weak reaction to dilute acid. Common localities include Brazil, India, the United States, Canada, and metamorphic mountain regions worldwide.
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