sedimentary
Siltstone Concretion
Carbonate-cemented Siltstone Concretion
Hardness: 3-5 (Mohs), Color: Tan to reddish-brown, Luster: Dull/Earthy, Crystal Structure: Microcrystalline, Cleavage: None, Shape: Spheroidal/Coiled
Identified More sedimentary →
Explore Siltstone Concretion in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3-5 (Mohs), Color: Tan to reddish-brown, Luster: Dull/Earthy, Crystal Structure: Microcrystalline, Cleavage: None, Shape: Spheroidal/Coiled
Formation & geological history
Formed by the precipitation of mineral cement within the spaces between sediment grains (silt or sand) around a nucleus, often during early diagenesis in sedimentary basins.
Uses & applications
Geological study, landscape decoration, and collecting; small ones are sometimes used as curiosities.
Geological facts
These often take on biomorphic or 'fossil-like' shapes, leading people to mistake them for dinosaur eggs, internal casts of seashells (steinkerns), or even petrified droppings.
Field identification & locations
Identified by their rounded, often bulbous or layered spherical shapes and different texture/hardness than the surrounding host rock. Commonly found in eroded shale or siltstone beds.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary