igneous
Granite Pebble
Granite (Phaneritic Acidic Igneous Rock)
Hardness: 6-7 (Mohs scale), Color: Mottled gray with black and white spots, Luster: Dull to vitreous, Crystal structure: Coarse-grained (phaneritic) composed of quartz, feldspar, and mica.
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Mottled gray with black and white spots, Luster: Dull to vitreous, Crystal structure: Coarse-grained (phaneritic) composed of quartz, feldspar, and mica.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. This specific specimen has been rounded by fluvial (water) or glacial erosion, indicating transport in a stream, river, or beach environment.
Uses & applications
While this specific pebble has low commercial value, granite is used extensively in construction (countertops, flooring) and as aggregate in road building.
Geological facts
Granite is the most common rock found in the Earth's continental crust. Because of its hardness, weathered granite pebbles like this one can survive for thousands of years in riverbeds.
Field identification & locations
Identify by its 'salt and pepper' appearance and visible interlocking crystals. It is found globally in mountain ranges, riverbeds, and glacial deposits. Test hardness by seeing if it scratches glass.
