metamorphic
White quartz-rich rock, likely quartzite
Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with minor feldspar, mica, or iron oxides
AI-generated identification · may be incorrectTypically Mohs 7, white to gray with rusty brown staining, and a vitreous to dull luster. Quartz grains are tightly interlocked; it is generally massive with poor or no cleavage and specific gravity around 2.6–2.7.
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Physical properties
Typically Mohs 7, white to gray with rusty brown staining, and a vitreous to dull luster. Quartz grains are tightly interlocked; it is generally massive with poor or no cleavage and specific gravity around 2.6–2.7.
Formation & geological history
Forms when quartz-rich sandstone is metamorphosed under substantial heat and pressure, commonly during mountain-building; its exact geological age cannot be determined from the photograph. Iron-bearing fluids may create the brown patches and vein-like staining.
Uses & applications
Used as crushed stone, aggregate, road material, building stone, and occasionally decorative slabs or lapidary material. Attractive pieces may be collected, though this specimen appears ordinary.
Geological facts
Quartzite commonly breaks across grains rather than around them, producing very hard, irregular fractures. The surface texture and possible granular patches are consistent with quartzite, though massive quartz or silicified rock is also possible.
Field identification & locations
Test hardness against glass: genuine quartzite should scratch it; inspect a fresh break for interlocking quartz grains. Common worldwide in metamorphic belts, including the Appalachians, Rocky Mountains, and Precambrian shields.
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