Sphericity
In geology sphericity is a parameter of how a spherical body.
Definition
The concept of sphericity was defined in 1935 by the geologist Hakon Wadell. The sphericity of a body K is the ratio of the surface of a sphere of equal volume to the surface of the body:
Wherein the volume of the body and the surface thereof respectively.
Application
In sedimentology and soil micromorphology the sphericity is used as an approximation for the grain shape. Since a calculation would be too expensive, it is usually estimated by comparing panels allowing a determination of grain rounding. The sphericity is then given not as a number but by classification (eg prismoidal, subprismoidal, spherical, subdiskoidal, discoidal ).