What other graphical methods can be used to represent weathering? Context:

For one of my reports I have taken samples of a rock from an adjacent creek. I have done XRD analysis to get compositions of calcium, potassium and aluminium.

My question:

I know about ternary diagrams, this is the base graphical method I will be using. However, what other basic methods could I employ to emphasize the effects of weathering in this experiment? The following data is what I plan on using.
First of all, you probably used XRF, and not XRD. XRF is a method used to obtain chemical compositions. XRD is used to obtain crystal structures.

A ternary diagram would be indeed very useful in this case. Another thing you might want to try is ratios: a plot of Al vs. K/Ca or something similar. Potassium and calcium likely behave differently in different weathering regimes, so it could be useful to show it.