igneous
Granite
Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Mica)
Hardness: 6-7 on Mohs scale. Color: Mottled salt-and-pepper appearance with shades of white, pink, and grey/black. Luster: Dull to vitreous. Crystal structure: Coarse-grained phaneritic (visible crystals). Specific gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Mottled salt-and-pepper appearance with shades of white, pink, and grey/black. Luster: Dull to vitreous. Crystal structure: Coarse-grained phaneritic (visible crystals). Specific gravity: 2.63 to 2.75.
Formation & geological history
Formed from the slow crystallization of magma below the Earth's surface (intrusive). Most continental granite dates from the Precambrian to Cenozoic eras, found primarily in batholiths and continental crust.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, and monuments due to its durability. Small river-worn specimens like this are used in landscaping or as decorative stones.
Geological facts
Granite makes up much of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest and most durable common stones on Earth.
Field identification & locations
Identify by its interlocking 'salt and pepper' crystalline texture and extreme hardness (it will scratch glass). Commonly found in mountain ranges, glaciated areas, and as rounded pebbles on beaches or in riverbeds.
