anthropogenic (human-made) sedimentary-like material

Concrete with Aggregate

Composite construction material; primary matrix is Calcium Silicate Hydrate (C-S-H)

Hardness: 3-7 Mohs (variable by aggregate); Color: Grey, tan, or speckled; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None (conchoidal to irregular fracture)

Hardness: 3-7 Mohs (variable by aggregate)
Color: Grey, tan, or speckled
Luster: Dull/Earthy

Identified March 25, 2026More anthropogenic (human-made) sedimentary-like material →

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Physical properties

Hardness: 3-7 Mohs (variable by aggregate); Color: Grey, tan, or speckled; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None (conchoidal to irregular fracture)

Formation & geological history

Formed through the hydration reaction of Portland cement mixed with water, sand, and gravel. It is a modern material, though historical versions date back to the Roman Empire.

Uses & applications

Primary use in global infrastructure, including buildings, bridges, sidewalks, and roads. Also used for decorative masonry and sculpture.

Geological facts

Concrete is the most widely used man-made material in existence. The small blue-green fragment visible in the specimen is likely a stray piece of glass or a decorative 'exposed aggregate' mineral like slag or amazonite.

Field identification & locations

Identify in the field by its uniform grey matrix binding together various rounded or angular pebbles. Commonly found in urban environments. Not a geological specimen for collection.

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not a natural rock

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sedimentary (anthropogenic / man-made)

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metamorphic (man-made / anthropic)

Note on Image Identification: Textile

N/A (Anthropogenic material)

not a rock

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Anthropogenic Aluminum (Al)

mineral