igneous
Granite
Granite (Felsic Plutonic Rock)
Hardness: 6-7 Mohs; Color: Speckled gray, pink, and white; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Cleavage: Irregular/None; Specific gravity: 2.63 - 2.75
- Hardness
- 6-7 Mohs
- Color
- Speckled gray, pink, and white
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 Mohs; Color: Speckled gray, pink, and white; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Cleavage: Irregular/None; Specific gravity: 2.63 - 2.75
Formation & geological history
Formed from the slow cooling and solidification of magma deep within the Earth's crust (plutonic). Found in continental crust, often appearing in mountain ranges after millions of years of erosion.
Uses & applications
Extensively used in construction, flooring, kitchen countertops, monuments, and as aggregate for roads and railroads due to its durability.
Geological facts
Granite is one of the hardest substances in the world. Famous structures like Mount Rushmore are carved from granite. It is an 'intrusive' rock, meaning it cooled underground.
Field identification & locations
Identify by its interlocking 'salt and pepper' crystalline texture and the presence of visible quartz (glassy) and feldspar (blocky). Commonly found in cratons and mountain cores like the Sierra Nevada or the Appalachians.
