sedimentary

Sandstone Concretion

Septarian or Carbonate-cemented Sandstone Concretion

AI-generated identification · may be incorrect

Hardness: 3-7 (variable depending on cement type); Color: Grey, tan, or brown; Luster: Dull/Earthy; Crystal structure: Clastic/Granular; Cleavage: None; Specific Gravity: ~2.3-2.7

Hardness: 3-7 (variable depending on cement type)
Color: Grey, tan, or brown
Luster: Dull/Earthy

Identified April 10, 2026More sedimentary →

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Physical properties

Hardness: 3-7 (variable depending on cement type); Color: Grey, tan, or brown; Luster: Dull/Earthy; Crystal structure: Clastic/Granular; Cleavage: None; Specific Gravity: ~2.3-2.7

Formation & geological history

Formed by the precipitation of mineral cement (often calcite or silica) within the spaces between sediment grains, usually around a nucleus like a shell or leaf. These often date to the Eocene or Cretaceous periods and form in marine basins or arid sedimentary environments.

Uses & applications

Primarily of interest to collectors and geologists. Larger specimens can be used in landscaping or as decorative garden elements. Some specific types contain fossils or crystals.

Geological facts

Concretions are often mistaken for fossils, dinosaur eggs, or even man-made artifacts because of their symmetrical, rounded appearance. Large fields of these are often called 'pumpkin patches' or 'cannonball beds'.

Field identification & locations

Identify in the field by looking for rounded, spherical, or disc-shaped masses that are harder and more resistant to erosion than the surrounding host rock. Commonly found in desert plateaus and coastal cliffs.