Granite Cobble

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, and black. Luster: Dull (weathered) to vitreous (on fresh surfaces). Structure: Coarse-grained phaneritic. Cleavage: None (individual minerals have cleavage, but the rock fractures irregularly).

Formation & Geological History

Formed from the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen has been rounded by fluvial (river) or glacial transport over thousands of years.

Uses & Applications

Used extensively in construction (as aggregate), countertops, monuments, and as decorative landscaping stones.

Geological Facts

Granite is the primary component of the Earth's continental crust. Because it is resistant to acid rain and very hard, it is the most popular stone for outdoor monuments and headstones.

Field Identification & Locations

Identify by looking for a 'salt and pepper' appearance with visible crystals of quartz (clear/grey), feldspar (pink/white), and mica (black/shiny). Commonly found in riverbeds and mountainous regions.

Identified on: 4/24/2026

Mode: Standard