Granite (Weathered)

Physical Properties

Hardness: 6-7 (Mohs scale); Color: Tan, brown, and grey with rusty iron oxidation; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Cleavage: None in the rock itself, though feldspar grains show 2 planes.

Formation & Geological History

Formed from the slow subterranean cooling of silica-rich magma (plutonic). This specific specimen shows chemical weathering and iron oxidation, typical of exposure to water and oxygen in surface environments.

Uses & Applications

Used extensively in construction as dimension stone, countertops, road aggregate, and for monuments due to its durability.

Geological Facts

Granite makes up a large portion of the Earth's continental crust. Over time, the feldspar in granite can weather into kaolinite clay.

Field Identification & Locations

Identify in the field by visually spotting clear quartz grains, opaque feldspar, and dark speckles of mica or hornblende. Commonly found in mountain ranges or Shield areas like the Canadian Shield.

Identified on: 4/22/2026

Mode: Standard