igneous
Weathered granitic rock
Granite or granodiorite; chiefly quartz, feldspar, and mica/amphibole
AI-generated identification · may be incorrectCoarse-grained, speckled gray-brown rock with visible light feldspar/quartz and dark mafic minerals; typically Mohs 6–7, vitreous-to-dull luster, interlocking crystals, and no cleavage as a whole.
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Physical properties
Coarse-grained, speckled gray-brown rock with visible light feldspar/quartz and dark mafic minerals; typically Mohs 6–7, vitreous-to-dull luster, interlocking crystals, and no cleavage as a whole.
Formation & geological history
An intrusive igneous rock crystallized slowly from magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building events; surface weathering has altered its color and texture.
Uses & applications
Used as crushed aggregate, building stone, countertops, monuments, and landscaping material; this weathered fragment has little jewelry value.
Geological facts
Granite-like rocks are identified by their visible interlocking crystals rather than layers or vesicles; granodiorite contains more plagioclase and dark minerals than typical granite.
Field identification & locations
Common worldwide, especially in continental mountain belts and exposed batholiths. Check for quartz’s glassy grains, blocky feldspar, and dark mica or amphibole; acid testing and hardness testing can help distinguish it from sandstone or concrete.
