Triangular variation diagrams

The two main types of variation diagram currently used by geochemists are considered in this section — bivariate plots and triangular variation diagrams. 

A. triangular variation diagram showing Alkalis (Na20 +... 

Triangular Triangular variation digrams are used when it is necessary to show simultaneous variation change between three variables. However, this practice is not recommended and diagrams bivariate plots are to be preferred, since both the computation of the plotting parameters and the interpretation of the resultant trends raise a number of important problems (see Section 2.7). 

That is, the amounts of B and C are referred to a constant amount of A. It should be remembered that in the triangular diagram a line parallel to one of the sides indicates, at a given temperature, a constant amount of the component represented by the opposite corner of the triangle and hence, points in plane parallel to one face of a right prism, will indicate, for different temperatures, variation in the amounts of two components, but constancy in the amount of the third. See also Janecke, Z. anorgan, Ckem. 1906, 51, 132. 

All possible compositions of the ternary mixture are represented by points on the triangle. The vertices correspond to the pure components and the sides to their binary mixtures, whereas the points inside the triangle represent mixtures of three components. The variation of a given property with the composition of the mixture can be described by a response surface drawn above the triangle, as shown in Fig. 7.2b. Representing this surface by its contour curves we obtain a triangular diagram, as illustrated in Fig. 7.2c7 ... 

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