Granite

Physical Properties

Hardness: 6-7 Mohs; Color: Pinkish-grey with black and white grains; Luster: Vitreous to dull; Crystal structure: Phaneritic (visible interlocking crystals); Cleavage: Indistinct; Specific Gravity: 2.63-2.75

Formation & Geological History

Formed from the slow crystallization of silica-rich magma beneath the Earth's surface (intrusive). This specific rounded shape (boulder) likely results from mechanical weathering and transport, potentially as a glacial erratic or river rock.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base.

Geological Facts

Granite makes up a large part of the Earth's continental crust. It is one of the hardest and most durable natural stones, which is why it has been used since ancient Egypt for building pyramids and obelisks.

Field Identification & Locations

Identify in the field by its 'salt and pepper' appearance and interlocking crystalline texture. Look for visible quartz (glassy), feldspar (opaque white/pink), and mica (black flakes). Commonly found in mountainous regions or as glacial debris.

Identified on: 4/30/2026

Mode: Standard