igneous
Granite
Phaneritic Felsic Intrusive Igneous Rock
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (tan, white, and black). Luster: Dull to vitreous. Crystal structure: Phaneritic (visible interlocking crystals). Composition: Primarily quartz, alkali feldspar, and plagioclase feldspar, with minor mica or amphibole.
- Hardness
- 6-7 on Mohs scale
- Color
- Salt-and-pepper (tan, white, and black)
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (tan, white, and black). Luster: Dull to vitreous. Crystal structure: Phaneritic (visible interlocking crystals). Composition: Primarily quartz, alkali feldspar, and plagioclase feldspar, with minor mica or amphibole.
Formation & geological history
Formed from the slow crystallization of magma below the Earth's surface (plutonic). It is found in continental crust and is often associated with mountain-building events from the Precambrian to Cenozoic eras.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monuments. It is also a popular specimen for educational rock kits.
Geological facts
Granite is the most common igneous rock found in Earth's continental crust. Because it is so hard and durable, it was the preferred building material for the pyramids and temples of Ancient Egypt.
Field identification & locations
Identify in the field by its speckled, coarse-grained appearance and hardness (it will scratch glass). Commonly found in eroded mountainous regions and riverbeds near batholiths.
