Anthropogenic (Man-made)

Asphalt (Road Aggregate)

Bituminous Conglomerate / Asphalt Concrete

Hardness: Variable (Bitumen is 1-2, stones are 6-7); Color: Black, charcoal grey, or weathered silver-grey; Luster: Dull to greasy; Structure: Granular/Clastic texture with angular aggregate; Cleavage: None

Hardness: Variable (Bitumen is 1-2, stones are 6-7)
Color: Black, charcoal grey, or weathered silver-grey
Luster: Dull to greasy

Identified March 21, 2026More anthropogenic (man-made) →

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Physical properties

Formation & geological history

Formed through industrial processes mixing mineral aggregate (crushed stone, sand, gravel) with a heavy petroleum-based binder (bitumen). This specimen appears to be a weathered or broken chunk of road surfacing.

Uses & applications

Primary use is in road construction, parking lots, and pavement. It is also highly recyclable, being one of the most reused construction materials in the world.

Geological facts

While it looks like a natural rock (Conglomerate), asphalt is a man-made composite. Natural asphalt (bitumen) has been used since ancient times by the Sumerians to waterproof boats and by Egyptians for mummification.

Field identification & locations

Identify by its smell (faint oil or tar scent when heated), presence of perfectly crushed angular stones, and its location (usually found near infrastructure). For collectors, this is considered a 'leaverite' (leave 'er right there) as it has no geological value.

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