metamorphic
Weathered quartz-rich rock, likely quartzite or silicified sandstone
Quartzite; predominantly microcrystalline to granular SiO₂, possibly with iron-oxide impurities
AI-generated identification · may be incorrectHardness about 7 Mohs; white, cream, tan, and rusty brown; vitreous to dull earthy luster; interlocking quartz grains with no obvious cleavage and irregular fracture. The rough, weathered surface and massive texture are consistent with quartzite, though the image alone cannot exclude silicified sandstone or quartz vein…
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Physical properties
Hardness about 7 Mohs; white, cream, tan, and rusty brown; vitreous to dull earthy luster; interlocking quartz grains with no obvious cleavage and irregular fracture. The rough, weathered surface and massive texture are consistent with quartzite, though the image alone cannot exclude silicified sandstone or quartz vein material.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized during metamorphism, commonly during regional mountain-building; its age depends on the original sandstone and local tectonic history. Iron oxides likely produced the tan-to-brown staining through weathering.
Uses & applications
Crushed quartzite is used for aggregate, road base, and silica products; sound decorative pieces may be used as landscaping stone or lapidary material. It is generally not gem-grade.
Geological facts
Quartzite commonly preserves faint bedding or sandy texture but breaks across grains rather than around them. A steel file should have difficulty scratching fresh quartz-rich surfaces.
Field identification & locations
Common in metamorphic belts worldwide, including the Appalachian Mountains, Rocky Mountains, India, Brazil, and Scandinavia. Confirm by testing a fresh surface: quartzite scratches glass and shows abundant sparkling quartz grains; dilute acid should not fizz unless carbonate minerals are present.
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