Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Mottled white, grey, and black. Luster: Vitreous to dull. Structure: Coarse-grained phaneritic texture with interlocking crystals of quartz, feldspar, and mica. Cleavage: Indistinct on the rock as a whole.

Formation & Geological History

Formed by the slow crystallization of magma below Earth's surface in continental crust. It can date back billions of years (Archean era) to more recent mountain-building events. Typically found in batholiths and core sections of mountain ranges.

Uses & Applications

Used extensively in construction for countertops, floor tiles, paving stones, and memorial monuments due to its durability and aesthetic appeal. Also used as crushed stone in roadbeds.

Geological Facts

Granite is the most common igneous rock found on Earth's continents. It makes up much of the continental crust. Because it is so hard and resistant to erosion, it often forms the heart of major mountain ranges like the Sierra Nevada and the Himalayas.

Field Identification & Locations

Identify by its interlocking 'salt and pepper' crystalline texture where minerals are large enough to see with the naked eye. Look for glassy quartz, blocky white/pink feldspar, and flaky black mica or hornblende grains. Common worldwide in continental shield areas.

Identified on: 4/15/2026

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