igneous
Granite
Phaneritic plutonic rock (High silica)
AI-generated identification · may be incorrectHardness: 6-7 (Mohs), Color: gray and white mottled with reddish iron staining, Luster: dull to vitreous, Structure: coarse-grained phaneritic, SG: 2.63 to 2.75
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Physical properties
Hardness: 6-7 (Mohs), Color: gray and white mottled with reddish iron staining, Luster: dull to vitreous, Structure: coarse-grained phaneritic, SG: 2.63 to 2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonic). This process allows large crystals of quartz, feldspar, and mica to grow. Can date from billions to millions of years old.
Uses & applications
Used in construction, countertops, monuments, road gravel, and as dimension stone due to its durability and resistance to weathering.
Geological facts
Granite makes up a large part of the Earth's continental crust. The reddish-orange color on the surface of this specimen is likely limonite or hematite staining from the oxidation of iron-bearing minerals.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz and feldspar. It is found in massive plutons or mountain ranges where erosion has exposed the deep crust.
