Anthropogenic (Man-made material mimicking sedimentary rock)

Concrete Fragment

Hardened Portland Cement Composite

Hardness: 3-7 (variable based on aggregate); Color: Gray to white matrix with multicolored pebbles; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None (irregular fracture); Specific Gravity: 2.2-2.5

Hardness: 3-7 (variable based on aggregate)
Color: Gray to white matrix with multicolored pebbles
Luster: Dull/Earthy

Identified March 16, 2026More anthropogenic (man-made material mimicking sedimentary rock) →

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Physical properties

Formation & geological history

Formed through a chemical hydration process where water is mixed with Portland cement and mineral aggregates. While the components (sand, gravel) are geologically old, the specimen is modern (typically less than 100 years old).

Uses & applications

Used globally in construction for infrastructure, buildings, roads, and bridges. This specific piece appears to be a weathered fragment or 'clast' of pavement.

Geological facts

Concrete is the most widely used man-made material on Earth. When found in nature, worn by water or erosion, it is sometimes colloquially referred to as 'Anthropocene conglomerate' or 'Technofossil'.

Field identification & locations

Identified in the field by its gray cementitious matrix holding together unsorted, rounded or angular river stones/sand. Commonly found in urban environments or near demolition sites. It lacks the natural layering or crystalline matrix found in real conglomerate rock.

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