igneous
Granite Pebble
Granite (composed primarily of Quartz SiO2, Feldspar KAlSi3O8, and Biotite/Hornblende)
Hardness: 6-7 (Mohs scale), Color: Pink, orange, white and black mottled pattern, Luster: Vitreous when polished, Crystal structure: phaneritic (granular), Clavage: Indistinct, Specific gravity: 2.63 - 2.75
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Pink, orange, white and black mottled pattern, Luster: Vitreous when polished, Crystal structure: phaneritic (granular), Clavage: Indistinct, Specific gravity: 2.63 - 2.75
Formation & geological history
Formed from the slow crystallization of magma below the Earth's surface during the Precambrian to Cenozoic eras. This specific specimen appears to be water-worn into a smooth pebble shape.
Uses & applications
Commonly used in construction, countertops, and abrasive materials; polished pebbles like this are used for landscaping, aquarium decor, and pocket stones.
Geological facts
Granite is the most common igneous rock found on Earth's continents. It is the building block of many famous mountain ranges like the Sierra Nevada and the Himalayas.
Field identification & locations
Identify in the field by its 'salt and pepper' or mottled appearance with visible interlocking crystals of different colors. It is frequently found in riverbeds and glacial deposits.
