igneous
Granite
Phaneritic Felsic Igneous Rock
Hardness: 6-7 Mohs; Color: Gray with salt-and-pepper flecks (white/gray quartz/feldspar and black biotite/hornblende); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Cleavage: Distinct in feldspars, none in quartz.
- Hardness
- 6-7 Mohs
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Gray with salt-and-pepper flecks (white/gray quartz/feldspar and black biotite/hornblende); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Cleavage: Distinct in feldspars, none in quartz.
Formation & geological history
Formed through the slow crystallization of magma below the Earth's surface (intrusive). This specimen shows a coarse-grained texture indicating long cooling times in the continental crust.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monuments due to its durability and resistance to weathering.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Unlike oceanic crust which is mostly basalt, the continents are 'buoyant' because they are made of less-dense granitic rocks.
Field identification & locations
Identify by looking for interlocked crystals of quartz (glassy gray/white) and feldspar (blocky opaque white/pink). It will scratch glass easily. Common in mountain ranges and glacial deposits.
