igneous
Granite
Phaneritic plutonic rock (SiO2 rich)
Hardness: 6-7 on Mohs scale; Color: Greyish-white with black and pink specks; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained) with visible quartz, feldspar, and mica; Specific gravity: 2.63-2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Greyish-white with black and pink specks
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Greyish-white with black and pink specks; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained) with visible quartz, feldspar, and mica; Specific gravity: 2.63-2.75
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. These plutons can be millions to billions of years old, often exposed by erosion and tectonic uplift. Common in continental crust.
Uses & applications
Extensively used in construction, countertops, monuments, paving stones, and as crushed stone for road base and railroad ballast. Highly valued for its durability and aesthetic appeal.
Geological facts
Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. Formed deep underground, it is only visible once the overlying material has been eroded away.
Field identification & locations
Identify by its 'salt and pepper' appearance and large, interlocking mineral grains. Found in many mountainous and hilly regions worldwide. Collectors often look for examples with large crystals or unique coloration.
