metamorphic
Quartz-rich metamorphic rock, likely quartzite
Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with feldspar or mica
AI-generated identification · may be incorrectHardness about 7 Mohs; pale gray to bluish-gray, massive and granular, with a vitreous to dull luster. Interlocking quartz grains and irregular fractures are typical; cleavage is absent and specific gravity is about 2.65.
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Physical properties
Hardness about 7 Mohs; pale gray to bluish-gray, massive and granular, with a vitreous to dull luster. Interlocking quartz grains and irregular fractures are typical; cleavage is absent and specific gravity is about 2.65.
Formation & geological history
Forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism, commonly from Precambrian to younger mountain-building events.
Uses & applications
Used as crushed stone, aggregate, paving and building stone; attractive pieces may be collected, though this specimen appears common and unpolished.
Geological facts
Quartzite is generally harder and more resistant to weathering than its sandstone precursor. The image may also represent quartz-rich gneiss or a silicified rock, but visible texture favors quartzite.
Field identification & locations
Identify it by its hardness, sugary granular texture, and quartz-rich appearance; it should scratch glass and resist abrasion. Common in metamorphic mountain belts worldwide, including the Appalachians, Rockies, Alps, and shield regions.
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