Granodiorite

Physical Properties

Hardness: 6-7 (Mohs scale); Color: Salt-and-pepper (white, grey, black); Luster: Phaneritic (crystalline); Crystal structure: Granular/Coarse-grained; Specific gravity: approx. 2.6-2.7

Formation & Geological History

Formed from the slow cooling of silica-rich magma beneath the Earth's surface. Often associated with continental arc magmatism and mountain building (orogeny) during various geological eras from the Precambrian to Cenozoic.

Uses & Applications

Commonly used in construction as crushed stone or 'granite' countertops, paving stones, and memorial monuments. It is also a source rock for various metallic ores.

Geological Facts

Granodiorite is the most common intrusive rock found in the Earth's continental crust. Famous examples include the Rosetta Stone, which was carved into a block of granodiorite, and many of the peaks in the Sierra Nevada batholith.

Field Identification & Locations

Identify in the field by its medium-to-coarse-grained 'salt-and-pepper' appearance. Unlike true granite, it contains more plagioclase feldspar than orthoclase. Found in large batholiths globally.

Identified on: 4/17/2026

Mode: Standard