igneous
Tumbled quartz-rich rock, likely granite or granitic gneiss
Granite/granitic gneiss; chiefly quartz (SiO₂), feldspars, and minor mica/amphibole
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pale gray to cream, granular texture, and mostly dull to slightly vitreous luster. Interlocking quartz and feldspar grains are visible, with possible dark mica or amphibole; no clear cleavage as a whole rock.
Identified More igneous →
Explore Tumbled quartz-rich rock, likely granite or granitic gneiss in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 6–7 Mohs; pale gray to cream, granular texture, and mostly dull to slightly vitreous luster. Interlocking quartz and feldspar grains are visible, with possible dark mica or amphibole; no clear cleavage as a whole rock.
Formation & geological history
Likely formed from slowly cooled silica-rich magma, or metamorphosed granite, during Precambrian to younger continental crust formation. The rounded shape appears naturally water-worn or mechanically tumbled.
Uses & applications
Commonly used as construction aggregate, dimension stone, landscaping gravel, and decorative polished stone; generally low jewelry value.
Geological facts
The pale, blocky grains are consistent with feldspar, while translucent glassy grains suggest quartz. Exact identification requires a fresh surface, hardness testing, and possibly thin-section or chemical analysis.
Field identification & locations
Common in continental shields and river gravels worldwide; identify by its coarse interlocking grains, quartz-like translucency, and inability to scratch with a steel knife in quartz-rich areas. A magnet test may detect minor magnetite.
