igneous
Weathered quartz-rich pebble
Likely quartzite or felsic granitoid fragment; predominantly SiO₂ quartz with minor feldspar and dark iron-bearing minerals
AI-generated identification · may be incorrectPale cream, fine- to medium-grained, subrounded and weathered, with a dull to sugary vitreous luster and dark inclusions. Quartz hardness is about Mohs 7; cleavage is absent, though the exact rock cannot be confirmed from the image alone.
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Physical properties
Pale cream, fine- to medium-grained, subrounded and weathered, with a dull to sugary vitreous luster and dark inclusions. Quartz hardness is about Mohs 7; cleavage is absent, though the exact rock cannot be confirmed from the image alone.
Formation & geological history
Probably eroded from a quartz-rich igneous or metamorphic outcrop and rounded by stream or shoreline transport; its formation may range from Precambrian to much younger depending on source rock.
Uses & applications
As an ordinary pebble it has little commercial use, though quartzite is used as aggregate, paving stone, and ornamental material; attractive pieces may be collected or polished.
Geological facts
The dark spots may be biotite, hornblende, magnetite, or iron-oxide staining rather than fossils. A glassy scratch test and close examination of grain boundaries help distinguish quartzite from granite.
Field identification & locations
Common in stream gravels, beaches, glacial deposits, and weathered bedrock worldwide. It should scratch ordinary glass but not be scratched by a steel knife; acid reaction would suggest carbonate contamination.
