igneous
Granite
Intrusive igneous felsic rock
Hardness (Mohs): 6-7; Color: salt-and-pepper (white k-feldspar/quartz and black biotite/hornblende); Luster: dull to vitreous; Structure: phaneritic (coarse-grained crystals visible to the naked eye); Specific gravity: 2.65-2.75.
- Luster
- dull to vitreous
Identified More igneous →
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Physical properties
Hardness (Mohs): 6-7; Color: salt-and-pepper (white k-feldspar/quartz and black biotite/hornblende); Luster: dull to vitreous; Structure: phaneritic (coarse-grained crystals visible to the naked eye); Specific gravity: 2.65-2.75.
Formation & geological history
Formed from the slow cooling and crystallization of silica-rich magma deep within the Earth's crust. Most granite formations range from the Precambrian to Cenozoic eras.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, monuments, and as aggregate for roads.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Famous outcrops include Yosemite's El Capitan and Mount Rushmore.
Field identification & locations
Identify by its 'salt and pepper' appearance and visible interlocking crystals. It is ubiquitous in mountainous regions and continental shields. Collectors look for large crystals or unusual inclusions like garnets.
