arenite

Arenite is a clastic sedimentary rock in which the clastic particles are sand-sized, typically between 0.062 and 2 millimeters in diameter, and the rock contains little to no clay or other fines as a matrix. In many classifications, arenite denotes a sandstone with a low matrix content, meaning most of the rock’s volume is composed of sand grains and the cementing material is limited.

Compositionally, arenites are described by their dominant mineral grains. Quartz arenite is the most quartz-rich type, often with more than 90% quartz and little feldspar or lithic material. Arkose or feldspathic arenite contains a significant fraction of feldspar, indicating shorter transport and less chemical weathering. Litharenite or lithic arenite contains substantial lithic (rock) fragments. The nomenclature reflects the degree of chemical and physical weathering the source material has undergone, as well as transport distance.

Depositional environments for arenites vary. Quartz arenites commonly form in stable, mature sands from environments such as deserts (aeolian sand dunes) or pristine shorelines, and they are often well sorted and well rounded. Arkose and litharenite tend to originate from less mature sands transported a shorter distance from proximal sources, such as rivers or nearshore settings. Diagenesis, including cementation by silica, carbonate, or iron oxides, can reduce porosity and permeability.

In geology and petroleum geology, arenites are important for understanding sedimentary provenance, transport history, and reservoir quality. Their physical properties—grain size, sorting, cement type, and matrix content—strongly influence porosity and permeability.