Asphalt (Road Aggregate)

Physical Properties

Hardness: 1-3 (Mohs), highly variable; Color: Black to dark grey; Luster: Dull to greasy; Structure: Heterogeneous mixture of mineral aggregates and bitumen; Specific Gravity: 2.3-2.5.

Formation & Geological History

Formed by mixing mineral aggregates (crushed rock, sand, gravel) with its binder, bitumen (petroleum-derived). Not a natural geological specimen, but a man-made road material.

Uses & Applications

Used primarily in road construction, pavement, parking lots, and roofing. Known for flexibility and durability under heavy loads.

Geological Facts

While asphalt occurs naturally in 'pitch lakes' like La Brea in Trinidad, most specimens found in urban environments are man-made asphalt concrete. It is one of the most recycled materials on the planet.

Field Identification & Locations

Identify by its dark color, porous appearance, and often a faint smell of tar if heated. It is commonly found near roadworks, driveways, or construction sites.

Identified on: 4/27/2026

Mode: Standard