metamorphic
Rounded quartz-rich pebble
Likely quartzite (mostly quartz, SiO₂); exact identification is uncertain from the photo
AI-generated identification · may be incorrectGray-white, opaque to slightly translucent patches, with a weathered tan-brown rind and dull to weakly glassy luster. Quartz hardness is 7 Mohs; quartzite has interlocking quartz grains and no cleavage, but the pebble’s smooth shape obscures its texture.
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Physical properties
Gray-white, opaque to slightly translucent patches, with a weathered tan-brown rind and dull to weakly glassy luster. Quartz hardness is 7 Mohs; quartzite has interlocking quartz grains and no cleavage, but the pebble’s smooth shape obscures its texture.
Formation & geological history
Likely formed when quartz sandstone was recrystallized by heat and pressure, then rounded by transport in water. Its age cannot be determined visually; quartzite occurs in rocks spanning much of Earth’s geologic history.
Uses & applications
Small pebbles are used for landscaping, crafts, and collecting; quartzite is also quarried as building and decorative stone.
Geological facts
Quartz-rich rocks resist chemical weathering and can survive long transport while becoming smoothly rounded.
Field identification & locations
Look for very hard material that scratches glass and lacks visible cleavage; a broken surface showing fused, interlocking quartz grains supports quartzite. Similar river or beach pebbles occur worldwide.
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