metamorphic
White quartz-rich pebble, likely quartzite
Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with minor feldspar or mica
AI-generated identification · may be incorrectHardness about 7 Mohs; pale gray-white, opaque, and finely granular with a dull to slightly vitreous luster. Massive, nonfoliated texture; typically no visible cleavage and fractures irregularly.
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Physical properties
Hardness about 7 Mohs; pale gray-white, opaque, and finely granular with a dull to slightly vitreous luster. Massive, nonfoliated texture; typically no visible cleavage and fractures irregularly.
Formation & geological history
Formed when quartz-rich sandstone was recrystallized under metamorphic heat and pressure, commonly during mountain building; its exact geological age cannot be determined from the image. The rounded shape indicates transport and abrasion in a river, beach, or glacial setting.
Uses & applications
Used as aggregate, road stone, landscaping material, and occasionally decorative stone; attractive pieces may be collected but are generally low value.
Geological facts
Quartzite is tougher and more resistant to weathering than the sandstone from which it formed. A steel nail should not scratch it, while quartzite may scratch ordinary glass.
Field identification & locations
Look for a sugary, interlocking quartz texture and consistent hardness throughout; unlike marble, it does not fizz with dilute hydrochloric acid. Common worldwide, especially in metamorphic mountain belts and stream gravels.
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