metamorphic
Rounded gray pebble, likely quartzite
Quartzite (predominantly crystalline quartz, SiO₂); identification is tentative from the image
AI-generated identification · may be incorrectGray-tan, rounded and smooth, with a dull to faintly sugary surface; quartzite is typically Mohs 7, nonmetallic, and has no cleavage. The specimen’s grain structure is not clear enough in this photo to confirm the identification.
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Physical properties
Gray-tan, rounded and smooth, with a dull to faintly sugary surface; quartzite is typically Mohs 7, nonmetallic, and has no cleavage. The specimen’s grain structure is not clear enough in this photo to confirm the identification.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized by heat and pressure during metamorphism. Its age depends on the source rock and metamorphic event and cannot be determined visually.
Uses & applications
Commonly used as building or landscaping stone, aggregate, and—when attractive and sound—as a decorative or lapidary material.
Geological facts
Quartzite is made of interlocking quartz grains and is generally harder and more resistant to weathering than its sandstone precursor.
Field identification & locations
A quartzite pebble often resists scratching by a steel knife and may scratch glass; look for fused, sugary-looking grains rather than loose sand grains. Rounded shape suggests transport by water or glacial ice; locality cannot be established from the image.
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