metamorphic

Reddish-purple river pebble, likely quartzite

Quartzite, composed mainly of quartz (SiO₂); exact identification is uncertain from the image alone.

AI-generated identification · may be incorrect

Fine-grained, opaque, muted reddish-purple with a smooth, rounded surface; quartzite typically has Mohs hardness 7, a nonmetallic luster, and no cleavage. The pictured stone’s grain and texture are not clear enough to confirm its mineral makeup.

Identified October 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Quartzite forms when quartz-rich sandstone is recrystallized by heat and pressure during metamorphism. Such pebbles are often rounded through transport in rivers or coastal settings; its geological age cannot be determined from appearance.

Uses & applications

Commonly used as decorative landscaping stone, aggregate, and occasionally as a lapidary material when attractive or unusually colored.

Geological facts

Iron-bearing minerals can lend quartzite red or purple hues. A useful check is whether it scratches glass and resists scratching by a steel knife, though these tests are not definitive.

Field identification & locations

Look for a hard, dense pebble with interlocking quartz grains and no obvious layering; quartzite occurs worldwide and commonly accumulates in river gravel. The image does not show enough detail to distinguish it confidently from other fine-grained rocks.