mineral

Quartz pebble in concrete

Quartz (SiO₂), embedded in Portland-cement concrete

AI-generated identification · may be incorrect

The central rounded, milky-white grain is likely quartz: Mohs hardness 7, vitreous-to-waxy luster, no cleavage, and conchoidal fracture. The surrounding gray, porous matrix is concrete containing sand and dark aggregate, not natural bedrock.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

This is a human-processed geological specimen: natural aggregate was mixed with cement and water, then hardened. The quartz grain may be geologically ancient, but the concrete is likely modern.

Uses & applications

Concrete is widely used for sidewalks, foundations, roads, and structures; quartz aggregate contributes hardness and durability. The embedded pebble has negligible jewelry or collector value.

Geological facts

The surrounding material appears manufactured because of its uniform cement paste, angular aggregate, and surface porosity. Quartz commonly survives weathering and is a frequent component of construction sand.

Field identification & locations

Identify quartz by its pale color, glassy appearance, hardness, and lack of cleavage; it should scratch ordinary glass. Since the specimen is embedded in concrete, classify the overall object as concrete rather than a natural rock.