igneous
Granite pebble
Granite; chiefly quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, speckled gray-tan rock with a granular texture and dull to slightly glassy luster. Mohs hardness is about 6–7; cleavage is absent as a rock, though feldspar crystals cleave, and specific gravity is roughly 2.6–2.7.
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Physical properties
Coarse-grained, speckled gray-tan rock with a granular texture and dull to slightly glassy luster. Mohs hardness is about 6–7; cleavage is absent as a rock, though feldspar crystals cleave, and specific gravity is roughly 2.6–2.7.
Formation & geological history
An intrusive igneous rock formed when silica-rich magma slowly crystallized deep underground, typically during ancient continental crust formation. The rounded shape indicates later weathering and stream or glacial transport.
Uses & applications
Commonly used as crushed aggregate, road material, building stone, countertops, monuments, and landscaping rock; this small pebble has negligible commercial value.
Geological facts
Its visible grains likely include pale quartz and feldspar with darker biotite or hornblende. Granite is the coarse-grained equivalent of volcanic rhyolite.
Field identification & locations
Identify it by its interlocking, salt-and-pepper grains and lack of layering or fossils; a knife generally will not scratch it, while quartz-bearing grains may scratch glass. Common worldwide, especially in continental mountain belts and stream gravels.
