metamorphic
Rounded quartz-rich pebble, likely quartzite
Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with minor feldspar or iron oxides
AI-generated identification · may be incorrectHardness about 7 Mohs; pale cream to gray, with a dull to subtly sugary/vitreous luster and no obvious cleavage. Dense, compact, and smoothly water-rounded; the pale surface and granular texture are consistent with quartzite, though sandstone is possible.
Identified More metamorphic →
Explore Rounded quartz-rich pebble, likely quartzite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 7 Mohs; pale cream to gray, with a dull to subtly sugary/vitreous luster and no obvious cleavage. Dense, compact, and smoothly water-rounded; the pale surface and granular texture are consistent with quartzite, though sandstone is possible.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during metamorphism; its exact geological age cannot be determined from the image. The specimen was likely transported and rounded in a stream, beach, or glacial gravel deposit.
Uses & applications
Quartzite is used as crushed aggregate, road stone, building stone, and decorative landscaping material; attractive pieces may be polished for collections. This small pebble has minimal commercial value.
Geological facts
Quartzite commonly fractures across quartz grains rather than around them and is typically harder than ordinary sandstone. A steel knife usually will not scratch it, while quartzite can scratch glass.
Field identification & locations
Common in metamorphic belts and derived gravels worldwide, including the Appalachians, Rocky Mountains, Scandinavia, and Australia. Test hardness and inspect a fresh break; acid reaction would suggest carbonate rock instead.
More like this
