igneous
Weathered granite or granitic gneiss
Granite; chiefly quartz, feldspar, and mica (exact identification is uncertain from the photograph)
AI-generated identification · may be incorrectCoarse-grained, gray, and speckled with a dull to weakly sparkling luster; typical Mohs hardness is 6–7, with poor cleavage overall. The pale patches may be exposed feldspar, quartz, or weathering crust rather than a separate mineral.
Identified More igneous →
Explore Weathered 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, gray, and speckled with a dull to weakly sparkling luster; typical Mohs hardness is 6–7, with poor cleavage overall. The pale patches may be exposed feldspar, quartz, or weathering crust rather than a separate mineral.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in the crust, commonly during Precambrian to younger continental mountain-building events; surface weathering rounded this specimen. If foliated internally, it could instead be granitic gneiss formed by metamorphism.
Uses & applications
Used widely as crushed aggregate, building stone, monuments, countertops, and landscaping rock; ordinary hand specimens have little jewelry value.
Geological facts
Granite is recognized by visible interlocking crystals rather than a glassy or layered texture. White weathering or lichen-like coatings can obscure the original mineral grains.
Field identification & locations
Common worldwide, including continental shields and mountain belts. Examine a fresh broken surface: quartz is gray and glassy, feldspar is white/pink, and mica forms dark reflective flakes; a streak test and hardness pick can help distinguish it from softer sedimentary rocks.
