igneous
Granite
Granite (Felsic Plutonic Rock)
Hardness: 6 to 7 Mohs; Color: Salt and pepper (white, gray, black, pink); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained, interlocking crystals); Cleavage: Dependent on mineral (Feldspar has 2 directions); Specific gravity: 2.63 to 2.75
- Hardness
- 6 to 7 Mohs
- Color
- Salt and pepper (white, gray, black, pink)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6 to 7 Mohs; Color: Salt and pepper (white, gray, black, pink); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained, interlocking crystals); Cleavage: Dependent on mineral (Feldspar has 2 directions); Specific gravity: 2.63 to 2.75
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface (intrusive). Most granite formations date back to the Precambrian or Paleozoic eras, found in the cores of mountain ranges or continental shields.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base and railroad ballast.
Geological facts
Granite makes up a large part of the continental crust. The name comes from the Latin 'granum', meaning a grain, in reference to its coarse-grained structure. It is the toughest of all building stones.
Field identification & locations
Identify by its 'salt and pepper' appearance with visible crystals of quartz (glassy), feldspar (opaque white/pink), and mica (shiny black flakes). Found globally in continental mountain ranges and tectonic plate boundaries.
