sedimentary

Concrete rubble

Anthropogenic conglomerate

Hardness: 3-7 (variable based on aggregate); Color: Grey, mottled with multi-colored pebbles; Luster: Dull, earthy; Structure: Granular, non-crystalline matrix; Specific Gravity: 2.3-2.5

Hardness: 3-7 (variable based on aggregate)
Color: Grey, mottled with multi-colored pebbles
Luster: Dull, earthy

Identified June 14, 2026More sedimentary →

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Physical properties

Hardness: 3-7 (variable based on aggregate); Color: Grey, mottled with multi-colored pebbles; Luster: Dull, earthy; Structure: Granular, non-crystalline matrix; Specific Gravity: 2.3-2.5

Formation & geological history

Formed through the industrial hydration of Portland cement mixed with water and aggregate (sand and gravel). This specific sample appears to be broken infrastructure from the modern era.

Uses & applications

Used universally in construction for buildings, roads, bridges, and sidewalks. Recycled rubble is often used as road base or sub-fill.

Geological facts

Concrete is the most widely used man-made material on Earth. When found in nature, it is often referred to as 'anthropogenic' or 'technogenic' rock, marking the human impact on geological layers.

Field identification & locations

Identify by its uniform grey matrix surrounding rounded river stones or crushed rock. Look for evidence of man-made shaping or proximity to developed areas. Often found in urban demolition sites.