igneous
Granite
Phaneritic Plutonic Felsic Rock (Granite)
Hardness: 6-7 on Mohs scale; Color: Pink, grey, and black mottled pattern; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained visible crystals); Composition: Orthoclase feldspar, Quartz, and Hornblende/Biotite.
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, grey, and black mottled pattern
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, grey, and black mottled pattern; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained visible crystals); Composition: Orthoclase feldspar, Quartz, and Hornblende/Biotite.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. This specimen appears to be a water-worn river stone or glacial erratic, likely dating from the Precambrian to Cenozoic eras depending on local basement rock.
Uses & applications
Widely used in construction, countertops, monuments, paving stones, and as crushed stone for road aggregate.
Geological facts
Granite makes up a large portion of the Earth's continental crust. It is one of the hardest and most durable natural stones, which is why it has been used in ancient Egyptian architecture and modern skyscrapers.
Field identification & locations
Identify by its 'salt and pepper' appearance with pinkish hues from potassium feldspar. Commonly found in mountainous regions or as rounded cobbles in glacial till and riverbeds throughout North America.
