igneous
Granite
Phaneritic Igneous Rock (composed primarily of Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 on Mohs scale. Color: Speckled white, pink, and grey with black minerals. Luster: Vitreous to dull. Crystal Structure: Coarse-grained (phaneritic) interlocking crystals. Cleavage: None (though individual minerals like feldspar have cleavage). Specific Gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Speckled white, pink, and grey with black minerals
- Luster
- Vitreous to dull
Identified More igneous →
Explore Granite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 on Mohs scale. Color: Speckled white, pink, and grey with black minerals. Luster: Vitreous to dull. Crystal Structure: Coarse-grained (phaneritic) interlocking crystals. Cleavage: None (though individual minerals like feldspar have cleavage). Specific Gravity: 2.63 to 2.75.
Formation & geological history
Formed by the slow crystallization of silica-rich magma beneath the Earth's surface (intrusive). Geological age varies from Precambrian to Cenozoic eras, typically associated with continental crust formation and mountain-building events.
Uses & applications
Widely used in construction for countertops, floor tiles, paving stones, and monuments. Also used as crushed stone for road base and railroad ballast. Minimal value in jewelry, primarily used for large-scale architectural projects.
Geological facts
Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest and most durable natural stones, which is why it has been used for monuments throughout human history.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible, interlocking crystals that do not show alignment or layers. Common in mountainous regions and glacial till. Collectors look for unique color variations or large crystal sizes (pegmatites).
