Igneous
Granite
Granite (Mainly Quartz, Feldspar, and Mica)
Hardness: 6-7 on Mohs scale; Color: typically white, pink, or gray with mottled dark spots; Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse-grained) crystalline texture; Cleavage: None in the mass rock, though individual mineral components like mica have perfect cleavage.
- Hardness
- 6-7 on Mohs scale
- Color
- typically white, pink, or gray with mottled dark spots
- Luster
- Vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: typically white, pink, or gray with mottled dark spots; Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse-grained) crystalline texture; Cleavage: None in the mass rock, though individual mineral components like mica have perfect cleavage.
Formation & geological history
Granite forms from the slow crystallization of magma below Earth's surface. This process occurs in batholiths and continental crust over millions of years, typically in tectonic zones. The cooling is slow enough to allow large crystals to grow.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, and memorial monuments. It is also crushed for use as aggregate in road building and ballast.
Geological facts
Granite makes up the majority of the Earth's continental crust. It is one of the hardest natural stones in the world and has been used for building since Ancient Egypt, notably in the Great Pyramid of Giza.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and interlocking crystals of roughly equal size. It will scratch glass but cannot be scratched by a steel knife. Common in mountainous regions and shield areas like the Canadian Shield or the Appalachians.
