igneous
Granite Pebble
Granite (Plutonic Igneous Rock)
Hardness 6-7 on Mohs scale; phaneritic (coarse-grained) texture; vitreous to dull luster; pinkish-grey to reddish matrix with distinct white feldspar and quartz crystals interlocked with minor dark mafic minerals (biotite/amphibole); specific gravity ~2.63-2.75.
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Physical properties
Hardness 6-7 on Mohs scale; phaneritic (coarse-grained) texture; vitreous to dull luster; pinkish-grey to reddish matrix with distinct white feldspar and quartz crystals interlocked with minor dark mafic minerals (biotite/amphibole); specific gravity ~2.63-2.75.
Formation & geological history
Formed deep underground through the slow cooling and crystallization of silica-rich felsic magma. Weathered and rounded over time by water or glacial action into a river pebble.
Uses & applications
Used widely in construction, dimension stone, aggregate, counter tops, decorative landscaping, and educational geology collections.
Geological facts
Granite makes up a major part of the Earth's continental crust. Over millions of years, erosion brings these underground formations to the surface, where water rounds them into smooth cobbles.
Field identification & locations
Identified by its visible interlocking mineral grains (quartz, potassium feldspar, and plagioclase). Extremely common in glaciated regions, riverbeds, mountain streams, and beaches worldwide.
