sedimentary
Sandstone Concretion
Septarian or Carbonate-cemented Sandstone Concretion
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 More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
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.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary