Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Grayish-white with pinkish-red spots (likely potassium feldspar). Luster: Dull to vitreous surface grains. Crystal structure: Phaneritic (coarse-grained) crystalline. Cleavage: Indistinct on the rock, though mineral components like feldspar show good cleavage. Specific gravity: 2.6-2.7.

Formation & Geological History

Formed through the slow cooling and crystallization of magma beneath Earth's surface (intrusive). The visible grains indicate a slow cooling process over thousands of years.

Uses & Applications

Widely used in construction for countertops, floor tiles, paving stones, and memorial monuments due to its durability and aesthetic appeal.

Geological Facts

Granite makes up the bulk of the continental crust. It is primarily composed of quartz and feldspar with minor amounts of mica or amphiboles. The pinkish color in this specimen suggests a significant presence of orthoclase feldspar.

Field Identification & Locations

Identify in the field by its blocky appearance, coarse interlocking crystals of different colors, and extreme hardness (it will scratch glass). It is commonly found in mountainous regions or areas where ancient mountain roots have been exposed by erosion.

Identified on: 4/15/2026

Mode: Standard