igneous
Granite pebble
Granite, composed mainly of quartz, feldspar, and dark mica (biotite)
AI-generated identification · may be incorrectCoarse, speckled white, gray, and black crystals with a granular texture; quartz hardness is 7 Mohs, feldspar 6, and biotite 2.5–3. Typically nonmetallic, with no consistent cleavage across the whole rock.
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Physical properties
Coarse, speckled white, gray, and black crystals with a granular texture; quartz hardness is 7 Mohs, feldspar 6, and biotite 2.5–3. Typically nonmetallic, with no consistent cleavage across the whole rock.
Formation & geological history
Granite forms when silica-rich magma cools slowly underground, allowing visible crystals to grow. Its age depends on its source; granites occur in continental crust ranging from Archean to recent geological history.
Uses & applications
Used as building and paving stone, countertops, monuments, and decorative aggregate; small pieces are common educational or collector specimens.
Geological facts
The contrasting light and dark grains are interlocking minerals, not paint or coating.
Field identification & locations
Recognize granite by its visible, interlocking quartz and feldspar grains with scattered dark mica. It occurs worldwide in continental mountain belts and exposed ancient crust; the image alone cannot establish the pebble’s exact source.
