Anthropogenic (Man-made)

Concrete Rubble with Aggregate

Hardened Portland Cement Paste with Coarse Aggregate

Hardness: 3-5 (Mohs scale); Color: Light grey matrix with dark basaltic aggregate; Luster: Dull/Earthy; Crystal Structure: Amorphous/Crystalline mix; Specific Gravity: ~2.4

Hardness: 3-5 (Mohs scale)
Color: Light grey matrix with dark basaltic aggregate
Luster: Dull/Earthy

Identified March 18, 2026More anthropogenic (man-made) →

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Physical properties

Hardness: 3-5 (Mohs scale); Color: Light grey matrix with dark basaltic aggregate; Luster: Dull/Earthy; Crystal Structure: Amorphous/Crystalline mix; Specific Gravity: ~2.4

Formation & geological history

Formed through the hydration of Portland cement mixed with water, sand, and stone. Not naturally occurring; created within the last 100 years. Found globally in urban environments.

Uses & applications

Primary construction material for buildings, roads, and infrastructure. This specific piece is waste/rubble.

Geological facts

Concrete is the most widely used man-made material in existence. It hardens via a chemical reaction called hydration, not by drying out.

Field identification & locations

Identify by its light grey, porous matrix and the presence of mixed-size rock inclusions (aggregate). Common in demolition sites or landscaping borders. Not a geological specimen of collector interest.

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