igneous
Granite (Pebble)
Granite (composed of Quartz, Feldspar, and Mica/Amphibole)
Mohs hardness 6-7, coarse-grained (phaneritic) texture, speckled color pattern containing white/cream orthoclase/plagioclase feldspar, translucent quartz, and dark biotite or hornblende inclusions. Dull to vitreous luster.
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Physical properties
Mohs hardness 6-7, coarse-grained (phaneritic) texture, speckled color pattern containing white/cream orthoclase/plagioclase feldspar, translucent quartz, and dark biotite or hornblende inclusions. Dull to vitreous luster.
Formation & geological history
Formed by the slow cooling and crystallization of felsic magma deep beneath the Earth's surface (intrusive plutonic environment). This particular specimen has been naturally smoothed and rounded by river or wave action into a pebble.
Uses & applications
Granite is widely used as a construction material, dimension stone, counter tops, and crushed stone for road aggregate. Smoothed beach or river pebbles are used in landscaping, aquariums, and home decor.
Geological facts
Granite makes up a large portion of the continental crust of Earth. Because it cools deep underground over thousands to millions of years, individual mineral grains grow large enough to be easily seen with the naked eye.
Field identification & locations
Identified by its salt-and-pepper or speckled phaneritic texture containing interlocked grains of light-colored feldspar/quartz and dark mafic minerals. Very common in mountainous regions, glaciated terrain, riverbeds, and ocean beaches worldwide.
