igneous
Granite (likely biotite granite)
Coarse-grained quartz–feldspar–biotite granitoid
AI-generated identification · may be incorrectHardness about 6–7 Mohs; speckled light gray, white, and black, with a granular crystalline texture and generally no cleavage as a whole. Quartz has a glassy luster; feldspar is typically vitreous to pearly. Specific gravity is about 2.63–2.75.
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Physical properties
Hardness about 6–7 Mohs; speckled light gray, white, and black, with a granular crystalline texture and generally no cleavage as a whole. Quartz has a glassy luster; feldspar is typically vitreous to pearly. Specific gravity is about 2.63–2.75.
Formation & geological history
Intrusive igneous rock formed by slow cooling and crystallization of silica-rich magma deep in Earth’s crust, commonly during Precambrian to Phanerozoic mountain-building events.
Uses & applications
Widely used as dimension stone, countertops, monuments, building facades, paving, and aggregate; attractive pieces are collected but usually have modest value.
Geological facts
The visible dark grains are probably biotite or amphibole, while pale grains are feldspar and quartz. Granite commonly weathers into rounded blocks and sandy grus.
Field identification & locations
Identify it by its coarse interlocking grains and quartz–feldspar–dark-mineral mixture; unlike basalt, it is light-colored and visibly crystalline. Common worldwide, especially in continental shields and mountain belts.
