Granitic rocks from the Wilson's Downfall‐Maryland area of northern New South Wales provide examples of albite and myrmekite of the intergranular and rim types. Following the views of Schwantke (1909), Spencer (1945), and Tuttle (1952), it is suggested that the process involved in the formation of secondary albite and myrmekite is one of unmixing of certain phases from an originally high temperature K–Na–(Ca) feldspar. The presence or absence of myrmekite is thought to be directly dependent on the original Ca content of the alkali‐feldspar.