metamorphic
Quartzite cobble
Quartzite, dominantly microcrystalline quartz (SiO₂), with iron-oxide staining and possible feldspar/mica
AI-generated identification · may be incorrectTypically Mohs hardness 7, nonmetallic waxy to glassy luster, massive granular texture, and no obvious cleavage; this specimen is rounded, gray-green and salmon-pink with weathered brown surfaces. The pink coloration likely reflects iron oxides or feldspar impurities.
Identified More metamorphic →
Explore Quartzite cobble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically Mohs hardness 7, nonmetallic waxy to glassy luster, massive granular texture, and no obvious cleavage; this specimen is rounded, gray-green and salmon-pink with weathered brown surfaces. The pink coloration likely reflects iron oxides or feldspar impurities.
Formation & geological history
Quartzite forms when quartz-rich sandstone is metamorphosed under substantial heat and pressure, commonly during mountain building; its exact geological age cannot be determined from the image. The rounded shape indicates later transport by water, glaciers, or shoreline action.
Uses & applications
Used as durable crushed stone, road aggregate, landscaping rock, and occasionally as building or decorative stone; attractive varieties may be cut or polished for ornaments.
Geological facts
Quartzite is considerably harder and more resistant to weathering than its sandstone precursor. Pink and gray color zoning commonly reflects impurities, alteration, or differing original sediment layers.
Field identification & locations
Identify it by its very hard, sugary-granular surface and quartz-rich appearance; it should scratch glass and resist a steel knife. Common in metamorphic mountain belts, glacial deposits, river gravels, and beaches.
More like this
