igneous
Granite
Granite (composed primarily of Quartz, Alkali Feldspar, and Plagioclase)
AI-generated identification · may be incorrectPhaneritic (coarsegrained) texture; Mohs hardness of 6-7; colors range from pink/orange to grey/white with black flecks; vitreous to dull luster; non-cleavable overall as a rock but individual minerals show cleavage.
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Physical properties
Phaneritic (coarsegrained) texture; Mohs hardness of 6-7; colors range from pink/orange to grey/white with black flecks; vitreous to dull luster; non-cleavable overall as a rock but individual minerals show cleavage.
Formation & geological history
Formed from the slow crystalline cooling of silica-rich magma deep underground (plutonic) over millions of years. This specific specimen is a water-worn river pebble or glacial cobble.
Uses & applications
Commonly used in construction for countertops, floor tiles, and monuments; as gravel in road building; and as decorative river stone in landscaping.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. The pink color in this specimen comes from potassium-rich orthoclase feldspar.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of varied colors. It is found globally in mountainous regions and glacial deposits.
