metamorphic
Rounded metamorphic pebble, likely quartzite or gneiss
Quartz-rich metamorphic rock; possibly foliated quartzite or gneiss
AI-generated identification · may be incorrectLight gray, fine- to medium-grained, rounded and naturally weathered; subdued satin to dull luster with faint wavy banding. Likely hardness around Mohs 6.5–7 if quartz-rich, with no obvious cleavage and moderate-to-high specific gravity (~2.6–2.7).
Identified More metamorphic →
Explore Rounded metamorphic pebble, likely quartzite or gneiss in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Light gray, fine- to medium-grained, rounded and naturally weathered; subdued satin to dull luster with faint wavy banding. Likely hardness around Mohs 6.5–7 if quartz-rich, with no obvious cleavage and moderate-to-high specific gravity (~2.6–2.7).
Formation & geological history
Probably formed when quartz-rich sandstone or granitic material was subjected to substantial heat and pressure, then eroded into a smooth pebble by water or glacial transport. Precise geological age and identification require a fresh broken surface or testing.
Uses & applications
Commonly used as landscaping stone, aggregate, or decorative/tumbled material; generally little jewelry value unless it displays attractive banding or unusual mineralization.
Geological facts
The rounded shape reflects abrasion during transport, while the subtle streaks may indicate foliation, compositional layering, or surface weathering. A glass-scratch test can help distinguish quartz-rich rock from softer limestone or concrete.
Field identification & locations
Common in streambeds, beaches, glacial deposits, and areas underlain by quartzite or metamorphic basement rocks. Test whether it scratches glass and examine a fresh surface for interlocking quartz grains; acid testing and a close inspection are needed to exclude marble or concrete.
More like this
