igneous
Granite Pebble
Granite (composed primarily of Quartz, Potassium Feldspar, Plagioclase, and Biotite/Amphibole)
Hardness 6-7 on Mohs scale. Color ranges from pink/salmon-pink (due to orthoclase feldspar) to gray and speckled green/black (minor minerals like biotite or hornblende). Luster is vitreous to dull on rounded water-worn surfaces. Phaneritic texture with interlocking crystals.
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Physical properties
Hardness 6-7 on Mohs scale. Color ranges from pink/salmon-pink (due to orthoclase feldspar) to gray and speckled green/black (minor minerals like biotite or hornblende). Luster is vitreous to dull on rounded water-worn surfaces. Phaneritic texture with interlocking crystals.
Formation & geological history
Formed by the slow crystallization of magma deep beneath the Earth's surface (intrusive igneous). This particular pebble has been weathered, eroded, and stream- or beach-rounded over millions of years.
Uses & applications
Commonly collected as river rocks, landscaping pebbles, crushed aggregate, dimension stone for construction/countertops, and for educational specimens.
Geological facts
Granite makes up a large portion of the Earth's continental crust. The pink hue in granite comes specifically from potassium-rich feldspar (orthoclase or microcline).
Field identification & locations
Identify by its interlocking granular texture, pinkish-orange orthoclase feldspar grains mixed with glassy quartz and dark minerals. Widely found in glacial till, riverbeds, and coastal beaches around the world.
