metamorphic
Weathered quartz-rich rock, possibly quartzite
Quartzite; predominantly microcrystalline quartz (SiO₂)
AI-generated identification · may be incorrectWhitish, dull-to-slightly vitreous, granular specimen with brown surface staining from iron oxides; quartz hardness is about Mohs 7, with no obvious cleavage and irregular fracture. Its texture is too indistinct in the image for certain identification.
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Physical properties
Whitish, dull-to-slightly vitreous, granular specimen with brown surface staining from iron oxides; quartz hardness is about Mohs 7, with no obvious cleavage and irregular fracture. Its texture is too indistinct in the image for certain identification.
Formation & geological history
Likely formed when quartz-rich sandstone was metamorphosed and recrystallized under heat and pressure, commonly during mountain-building; its precise geological age cannot be determined visually. It may also be weathered quartz or a quartz-rich vein fragment.
Uses & applications
Quartzite is used as crushed stone, road aggregate, building stone, and decorative material; attractive specimens may be collected but this piece appears low-grade.
Geological facts
Quartzite commonly resists scratching by a steel knife, unlike many softer white rocks. Brown coloration typically reflects limonite or hematite staining along fractures and weathered surfaces.
Field identification & locations
Common in metamorphic mountain belts and quartz-rich gravel deposits worldwide, including the Appalachians, Rocky Mountains, and many older shields. Confirm with a hardness test, acid test, and close inspection for fused quartz grains; a laboratory test may be needed.
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