igneous
Granite
Phaneritic plutonic felsic rock
Hardness: 6-7 on Mohs scale; Color: Pink, gray, and black speckles; Luster: Dull to vitreous; Crystal structure: Phaneritic (visible crystals); Cleavage: Distinct in feldspars; Specific gravity: 2.63-2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, gray, and black speckles
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, gray, and black speckles; Luster: Dull to vitreous; Crystal structure: Phaneritic (visible crystals); Cleavage: Distinct in feldspars; Specific gravity: 2.63-2.75
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). They take millions of years to cool, allowing large crystals to form. Common in continental crust and mountain ranges.
Uses & applications
Widely used for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road construction and railroad ballast.
Geological facts
Granite is one of the oldest and most durable rocks on Earth, making up the majority of the continental crust. The Egyptian pyramids are partly made of granite.
Field identification & locations
Identify by the 'salt and pepper' appearance of interlocking crystals including quartz (clear), feldspar (pink/white), and biotite or hornblende (black). Found in batholiths and shield areas like the Canadian Shield.
