metamorphic
Tumbled quartzite pebble
Quartzite, predominantly crystalline quartz (SiO₂)
AI-generated identification · may be incorrectHardness ~7 Mohs; pale cream to honey color, finely granular texture, and vitreous-to-waxy luster. Massive, interlocking quartz grains show no obvious cleavage; the smooth surface indicates natural water wear or tumbling.
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Physical properties
Hardness ~7 Mohs; pale cream to honey color, finely granular texture, and vitreous-to-waxy luster. Massive, interlocking quartz grains show no obvious cleavage; the smooth surface indicates natural water wear or tumbling.
Formation & geological history
Formed when quartz-rich sandstone was recrystallized under heat and pressure during metamorphism, commonly during mountain building; its exact age cannot be determined from the image. Resistant fragments accumulate in streambeds, beaches, and glacial deposits.
Uses & applications
Used as aggregate, paving and landscaping stone, decorative pebbles, countertops, and occasionally as a lapidary material. This ordinary tumbled piece has modest collector value.
Geological facts
Quartzite commonly breaks across grains rather than around them and is typically harder and more durable than its sandstone precursor.
Field identification & locations
Common in quartz-rich metamorphic terrains worldwide, including the Appalachian Mountains, Rocky Mountains, India, Brazil, and Scandinavia. It can scratch ordinary glass and does not fizz with dilute hydrochloric acid, distinguishing it from calcite-rich marble.
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