igneous
Granite pebble
Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz and feldspar with dark biotite or hornblende
AI-generated identification · may be incorrectGray, white, and black speckled appearance; interlocking crystals with a granular texture and no cleavage as a whole rock. Hardness is typically about 6–7 Mohs; the pictured pebble is rounded and appears naturally weathered.
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Physical properties
Gray, white, and black speckled appearance; interlocking crystals with a granular texture and no cleavage as a whole rock. Hardness is typically about 6–7 Mohs; the pictured pebble is rounded and appears naturally weathered.
Formation & geological history
Granite forms when silica-rich magma cools slowly underground, allowing visible crystals to grow. Its age cannot be determined from the image; granites range from Precambrian to recent geological periods.
Uses & applications
Granite is widely used for building stone, countertops, paving, and monuments; small rounded specimens are commonly collected or used decoratively.
Geological facts
Its pale minerals are usually quartz and feldspar, while dark flecks are commonly biotite or amphibole.
Field identification & locations
The mottled, interlocking grains and quartz hardness help distinguish granite from many sedimentary rocks. Granite occurs worldwide in continental crust; the pebble’s source cannot be established from the photo.
