Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Mottled black, white, and translucent grey. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained) interlocking crystals. Cleavage: Variable by mineral component, though granite itself lacks overall cleavage.

Formation & Geological History

Formed through the slow crystallization of magma below the Earth's surface (intrusive). It typically forms in continental crust above subduction zones or during continental collisions.

Uses & Applications

Extensively used in construction (countertops, floor tiles, paving stones), monuments, and as crushed stone for road base and railroad ballast.

Geological Facts

Granite makes up a large portion of the Earth's continental crust. Yosemite National Park's famous Half Dome and El Capitan are massive granite monoliths.

Field Identification & Locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and biotite mica. Look for it in mountain ranges and eroded riverbeds.

Identified on: 4/19/2026

Mode: Standard