When an originally homogeneous high$-$temperature mineral, containing cations of

considerably different size, is allowed to cool to low temperature, it always separates

into two $($or possibly more$)$ distinct crystalline minerals. The above phenomenon is

called exsolution. Please use the below equation and plot the curve of

$G_{\text{m}\text{i}\text{x}\text{i}\text{n}\text{g}}-$composition at high and low temperatures to explain the reason of the

occurrence of exsolution $.$

$G_{\text{m}\text{i}\text{x}\text{i}\text{n}\text{g}}=H_{\text{m}\text{i}\text{x}\text{i}\text{n}\text{g}}-T{S}_{\text{m}\text{i}\text{x}\text{i}\text{z}\text{g}}$