Rock Identifier
Concrete (Hydrated Portland Cement Aggregate Composite) — Anthropogenic Sedimentary (Man-made)
Anthropogenic Sedimentary (Man-made)

Concrete

Hydrated Portland Cement Aggregate Composite

Hardness: 3-7 on Mohs scale (variable based on aggregate); Color: Gray to light gray; Luster: Dull/Matte; Structure: Granular composite; Cleavage: None/Irregular fracture; Specific Gravity: 2.3 - 2.5

Hardness
3-7 on Mohs scale (variable based on aggregate)
Color
Gray to light gray
Luster
Dull/Matte

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Physical properties

Hardness: 3-7 on Mohs scale (variable based on aggregate); Color: Gray to light gray; Luster: Dull/Matte; Structure: Granular composite; Cleavage: None/Irregular fracture; Specific Gravity: 2.3 - 2.5

Formation & geological history

Formed through a chemical process called hydration where Portland cement (calcined limestone and clay) reacts with water to bind mineral aggregates (sand, gravel, or crushed stone); originated in modern form in the 19th century.

Uses & applications

Primary material for global infrastructure, including buildings, bridges, sidewalks, roads, and dams.

Geological facts

Concrete is the most widely used man-made material on Earth. The Romans used a form of volcanic ash concrete that has lasted for over 2,000 years, such as in the Pantheon dome.

Field identification & locations

Identified in the field by its uniform gray color, presence of visible sand/gravel grains, and brush marks or mold impressions; found universally in urban environments.