sedimentary

Sandstone Concretion

Sedimentary Concretion (Quartz-cemented sand)

Hardness of 6-7 on the Mohs scale, earthy luster, tan to brown color, and granular crystal structure with no cleavage.

Identified November 11, 2026More sedimentary →

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Physical properties

Hardness of 6-7 on the Mohs scale, earthy luster, tan to brown color, and granular crystal structure with no cleavage.

Formed through the precipitation of mineral cement within the pores of sandstone sediments, often around a nucleus, over millions of years.

Used primarily as decorative collector specimens, curiosities, or educational examples of geological precipitation.

These spherical or cubic-like rock formations are often mistaken for man-made artifacts or fossils due to their unusual geometric weathering.

Identified by its distinctive rounded or box-like shape protruding from eroding sedimentary layers; commonly found worldwide in sandstone formations.

Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion

Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image

Sandstone or Siltstone

Arenite (if sandstone)

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)