A Maucha diagram, or Maucha symbol, is a graphical representation of the major cations and anions in a chemical sample. R. Maucha published the symbol in 1932. Maucha Key

It is mainly used by biologists and chemists for quickly recognising samples by their chemical composition. The symbol is similar in concept to the

Stiff diagram A Stiff diagram, or Stiff pattern, is a graphical representation of chemical analyses, first developed by H.A. Stiff in 1951. It is widely used by hydrogeologists and geochemists to display the major ion composition of a water sample. A polygonal ...

. It conveys similar ionic information to the

Piper diagram A Piper diagram is a graphic procedure proposed by Arthur Maine Piper, Arthur M. Piper in 1944 for presenting water chemistry data to help in understanding the sources of the dissolved constituent salts in water. This procedure is based on the pre ...

, though in a more compact format that is suitable as a map symbol or for showing changes with time. The Maucha diagram is a special case of the

Radar chart A radar chart is a graphical method of displaying multivariate data in the form of a two-dimensional chart of three or more quantitative variables represented on axes starting from the same point. The relative position and angle of the axes i ...

and overcomes some of the limitations of the

Pie chart A pie chart (or a circle chart) is a circular Statistical graphics, statistical graphic which is divided into slices to illustrate numerical proportion. In a pie chart, the arc length of each slice (and consequently its central angle and area) ...

by having equal angles for all variables and consistently showing each variable in the same position. The star shape comprises eight kite-shaped polygons, the area of each of which is proportional to the concentration of an ion in milliequivalents per litre. The anions carbonate, bicarbonate, chloride and sulphate are on the left, while the cations potassium, sodium, calcium and magnesium are on the right. The total ionic concentration adds up to the area of the background circle, the total anion concentration adds up to the left semicircle and the total cation concentration adds up to the right semicircle. A method for drawing the diagram in R is available on GitHub. Broch and Yake modified Maucha's original fixed-size diagram by scaling for concentration. Further scaling using the logarithm of the ionic concentration enables the plotting of a wide range of concentrations on a single map. Silberbauer, M.J., 2011. Multivariate Point Data Visualisation - Geographical Information Systems Developments to Aid in Water Quality Management. The 14th AGILE International Conference on Geographic Information Science. URL http://www.riv.co.za/cv/pdf/Multivariate%20Point%20Data%20Visualisation%20-%20Geographical%20Information%20Systems%20Developments%20to%20Aid%20in%20Water%20Quality%20Management%20handout.pdf

References

{{reflist Analytical chemistry Diagrams