igneous
Weathered granite or granitic pebble
Granite; chiefly quartz, alkali feldspar, plagioclase, and minor mica/amphibole
AI-generated identification · may be incorrectLight gray, coarse crystalline, and granular with a dull-to-glassy luster; typical hardness is about 6–7 Mohs, with no dominant cleavage and specific gravity around 2.6–2.7. The image is blurred, so exact mineral identification is uncertain.
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Physical properties
Light gray, coarse crystalline, and granular with a dull-to-glassy luster; typical hardness is about 6–7 Mohs, with no dominant cleavage and specific gravity around 2.6–2.7. The image is blurred, so exact mineral identification is uncertain.
Formation & geological history
Granite forms when silica-rich magma cools slowly deep within continental crust, producing visible interlocking crystals; specimens may be Precambrian to Phanerozoic in age and later released by erosion. Its rounded shape suggests transport and weathering as a pebble.
Uses & applications
Used extensively as dimension stone, countertops, monuments, aggregate, and paving; small pieces are common geological teaching and collection specimens. This ordinary pebble has little commercial value.
Geological facts
Quartz commonly appears glassy gray, feldspar white or pink, and mica as dark flakes; rusty patches may reflect iron-oxide weathering. Granite is the intrusive equivalent of volcanic rhyolite.
Field identification & locations
Identify it by its speckled interlocking texture, lack of layering, and inability to scratch glass only weakly or not at all; a hand lens and streak, hardness, and acid tests help distinguish it from quartzite or concrete. Common worldwide, especially in exposed continental mountain belts.
