igneous
Granite cobble
Granite; predominantly quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, pale gray rock with visible dark and light minerals; quartz hardness 7, feldspar 6, mica 2–3, generally vitreous to pearly luster and no prominent cleavage as a whole.
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Physical properties
Coarse-grained, pale gray rock with visible dark and light minerals; quartz hardness 7, feldspar 6, mica 2–3, generally vitreous to pearly luster and no prominent cleavage as a whole.
Formation & geological history
An intrusive igneous rock crystallized slowly from silica-rich magma deep in continental crust, commonly millions to billions of years old; later weathered into a rounded cobble.
Uses & applications
Used as aggregate, building and paving stone, monuments, countertops, landscaping rock, and garden specimens; this ordinary cobble has minimal commercial value.
Geological facts
The rounded shape indicates transport or prolonged weathering, while the speckled texture reflects interlocking crystals formed underground.
Field identification & locations
Identify granite by its visible interlocking quartz, feldspar, and mica grains and inability to scratch with a steel nail; common in continental mountain belts and glacial deposits. The image may also show a granite-like gneiss, but texture is insufficient for certainty.
