igneous
Weathered granite or granodiorite
Granite–granodiorite; primarily quartz, plagioclase and potassium feldspar with biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, gray-brown, massive and weathered, with a granular texture and faintly visible light/dark mineral grains; typical hardness is about 6–7 Mohs, vitreous to dull luster, and no prominent cleavage as a whole rock.
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Physical properties
Coarse-grained, gray-brown, massive and weathered, with a granular texture and faintly visible light/dark mineral grains; typical hardness is about 6–7 Mohs, vitreous to dull luster, and no prominent cleavage as a whole rock.
Formation & geological history
An intrusive igneous rock that crystallized slowly from magma deep in the continental crust, commonly during Precambrian to Mesozoic mountain-building events; surface weathering has darkened and rounded this specimen.
Uses & applications
Used for crushed stone, road aggregate, building stone, monuments, countertops and landscaping; this rough, weathered piece has little jewelry value.
Geological facts
Granite and granodiorite are distinguished mainly by feldspar proportions, which cannot be confirmed confidently from this photograph alone.
Field identification & locations
Common in continental mountain belts and glaciated terrains. Look for interlocking quartz and feldspar grains, a speckled texture, substantial weight, and resistance to scratching; a fresh broken surface or hand lens would improve identification.
