Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Mottled grey, white, and black with hints of pink; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Cleavage: None for the rock, though individual minerals like mica exhibit it; Specific Gravity: ~2.65 - 2.75.

Formation & Geological History

Formed from the slow subterranean cooling of silica-rich magma (plutons). Granite is found globally in continental crust and is common in ancient shields and mountain ranges, often dating back hundreds of millions to billions of years.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stones, and memorial monuments. It is also used as crushed aggregate for road construction.

Geological Facts

Granite forms the core of most continents. It is one of the hardest and most durable common stones, which is why it has been used since ancient Egypt for temples and pyramids.

Field Identification & Locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz and feldspar. It will not react with acid like limestone and can scratch glass.

Identified on: 4/15/2026

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