Granite Cobble

Physical Properties

Hardness: 6-7 Mohs; Color: Salt and pepper (white, grey, and black); Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Cleavage: Indistinct; Specific Gravity: 2.65-2.75

Formation & Geological History

Formed from the slow crystallization of magma below Earth's surface. This specific specimen shows evidence of being water-worn (rounded) in a stream, river, or glacial environment. Geological age varies widely by location, often millions of years old.

Uses & Applications

Used in construction, countertops, monuments, and as decorative stone in landscaping. Small rounded cobbles are often used for river rock decorations or drainage.

Geological Facts

Granite is the most common igneous rock found at the Earth's surface. It makes up the bulk of the continental crust. The word 'granite' comes from the Latin 'granum', meaning a grain.

Field Identification & Locations

Identify by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and mica. This rounded shape indicates it was transported by water over a long distance. Common in mountain ranges and riverbeds.

Identified on: 4/22/2026

Mode: Standard