igneous
Coarse-grained Granite
Granitoid (Felsic Plutonic Rock)
Hardness: 6-7 Mohs; Color: Salt and pepper appearance with grey, white, and faint pink/green tones; Luster: Vitreous to dull; Crystal structure: Phaneritic (large visible crystals), equigranular; Cleavage: None for the rock, but component minerals (feldspar) show cleavage.
- Hardness
- 6-7 Mohs
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper appearance with grey, white, and faint pink/green tones; Luster: Vitreous to dull; Crystal structure: Phaneritic (large visible crystals), equigranular; Cleavage: None for the rock, but component minerals (feldspar) show cleavage.
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground. This slow process allows large crystals of quartz, feldspar, and mica to grow. This particular specimen shows weathering and possibly chlorite alteration (the green tint).
Uses & applications
Crushed stone for construction, architectural facade, countertops, and historical building material.
Geological facts
Granite makes up a large portion of the Earth's continental crust. El Capitan in Yosemite National Park is a famous massive granite monolith. The green tint in some specimens is often due to the hydrothermal alteration of dark minerals into chlorite or epidote.
Field identification & locations
Identify in the field by its phaneritic texture and lack of layering (non-foliated). It is found in tectonic regions and ancient cratons globally. To identify, look for interlocking crystals of quartz (clear/grey) and feldspar (white/pink).
