sedimentary

Concrete aggregate surface

Human-made cementitious composite; primarily calcium-silicate-hydrate cement with mixed silicate aggregate

AI-generated identification · may be incorrect

Gray, fine-grained cement paste surrounds angular fragments of dark basalt, light quartz/feldspar-rich rock, and tan aggregate; dull, noncrystalline surface. The aggregate components are commonly Mohs 5–7, but the composite’s apparent hardness varies; no geological cleavage or consistent crystal structure is visible.

Identified September 11, 2026More sedimentary →

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Physical properties

Formation & geological history

This is processed concrete, not a natural rock: Portland cement, water, sand, and crushed stone were mixed, placed, and hydrated. Its apparent age is modern and depends on construction history, typically decades or less.

Uses & applications

Used extensively for sidewalks, slabs, foundations, roads, and buildings; it has negligible collector or jewelry value.

Geological facts

The multicolored angular clasts are intentionally added aggregate, while the pale matrix is hydrated cement paste. Weathering can expose aggregate and produce surface pitting or cracking.

Field identification & locations

Identify it by the uniform cement matrix, artificially distributed angular stones, flat construction surface, and lack of natural bedding or crystal intergrowth. Common worldwide in urban infrastructure.