Stiff pattern

A Stiff Pattern (a.k.a. Stiff Diagram) is a graphical representation of chemical analyses, first developed by H.A. Stiff in 1951, and is most commonly used by hydrogeologists. A polygonal shape is created from four parallel horizontal axes extending on either side of a vertical zero axis. Cations are plotted in milliequivalents per liter on the left side of the zero axis, one to each horizontal axis, and anions are plotted on the right side. Stiff patterns are useful in making a rapid visual comparison between water from different sources.