sedimentary

Sandstone (or Siltstone Concretion)

Arenite / Quartzose Sandstone

Mohs hardness 6-7, dull earthy luster, fine to medium grainy texture, tan to buff color.

Identified October 30, 2026More sedimentary →

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Physical properties

Mohs hardness 6-7, dull earthy luster, fine to medium grainy texture, tan to buff color.

Formed by the compaction and cementation of mineral particles or rock fragments in alluvial, desert, or marine environments.

Commonly used as building and paving material, in decorative landscaping, and historically for grindstones.

Naturally rounded or discoidal sedimentary stones often form as concretions or are shaped by river and wave action over millennia.

Identifiable by its gritty sandpaper feel and porous surface; widely found in sedimentary basins and riverbeds globally.

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

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)