For example, on a diagram drawn using the axes logaSiO2,aq and logaMg+2(aH+)2 , the third axis along which the diagram is projected would be logaAl+3/(aH+)3 . If the logaSiO2,aq and logaMg+2/(aH+)2 values are appropriate for chlorite stability, chlorite will form if and only if there is sufficient Al+3 in solution to form chlorite. If there is not enough Al+3 in solution, the logaAl+3/(aH+)3 will be too low and the solution will be undersaturated with respect to solids. This appears to be the case with many of the specular hematite-bearing ores of the Superior district, Arizona.