igneous
Quartz-bearing granite or granitic gneiss
Granite; chiefly quartz (SiO₂), feldspar, and dark mica/amphibole
AI-generated identification · may be incorrectCoarse-grained, speckled gray-and-white rock with vitreous quartz and pale feldspar; hardness about 6–7, nonmetallic luster, interlocking crystals, and no prominent cleavage as a whole. The dark patches may be biotite mica or amphibole, while the surface appears naturally weathered or broken.
Identified More igneous →
Explore Quartz-bearing granite or granitic gneiss in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse-grained, speckled gray-and-white rock with vitreous quartz and pale feldspar; hardness about 6–7, nonmetallic luster, interlocking crystals, and no prominent cleavage as a whole. The dark patches may be biotite mica or amphibole, while the surface appears naturally weathered or broken.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep in the continental crust, commonly during Precambrian to Mesozoic intrusive events; if foliated, it may instead be metamorphosed granite (gneiss).
Uses & applications
Used as dimension stone, countertops, building aggregate, monuments, and landscaping rock; this small irregular specimen has mainly educational or modest collecting value.
Geological facts
Granite is identified by visible interlocking quartz and feldspar grains rather than sedimentary layers. A steel nail generally will not scratch it, but quartz can scratch glass.
Field identification & locations
Common worldwide, including continental mountain belts and old cratons; inspect a fresh surface for glassy gray quartz, blocky feldspar, and black mica, and distinguish it from concrete by the absence of uniform cement and manufactured aggregate.
