Myrmekite from the Charnockite Series of Amaravathi, Guntur District, Andhra Pradesh

A detailed description of myrmekite is furnished and its origin discussed in the light of the existing theories. Myrmekite is believed to be formed by exsolution, deriving both the components - quartz and plagioclase, which are held in solid solution in the form of albite and CaAl₂, Si₆O₁₆ in po:ash felspar. Myrmekite in norite is presumed to be formed due to the breakdown of anorthite molecule of the plagioclase releasing the required silica, thus making the plagioclase less basic than its parent. The granulite facies (charnockite environmental) conditions seem to be ideal for the formation of myrmekite by exsolution process.