sedimentary

Sandstone concretion

Arenite sedimentary rock (concretion/nodule)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs scale), Color: tan to reddish-brown (iron-stained), Luster: dull/earthy, Crystal structure: clastic (granular), Specific gravity: 2.2-2.8

Identified July 7, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Mohs scale), Color: tan to reddish-brown (iron-stained), Luster: dull/earthy, Crystal structure: clastic (granular), Specific gravity: 2.2-2.8

Formation & geological history

Formed by the precipitation of mineral cement (often calcite or iron oxide) within the spaces between sediment grains. This typically occurs in marine or terrestrial sedimentary basins over millions of years.

Uses & applications

Primarily of interest to collectors and geologists as curiosities; occasionally used in landscaping or as decorative garden stones.

Geological facts

Concretions are often mistaken for fossils, artifacts, or even meteorites because of their unusual rounded or biological-looking shapes. Some grow around a central nucleus like a pebble or fossil.

Field identification & locations

Identify in the field by its rounded or bulbous shape which differs from the surrounding bedding. Common in sandstone formations worldwide, especially in arid or coastal regions.