Abstract
Orthoclase cryptoperthites containing the albite component approximately at 35-50 percent are not homogenized below the liquidus but they obviously become homogeneous only after being transformed into the high-temperature form which is stable from about 820°C up to nearly the melting point. Our experiments show that the transformation may be reversible. Presumably, all orthoclase cryptoperthites, in spite of their compositions, show the same behavior mentioned above when heated. A suggestion of the possible mechanism of the transformation and a model of the perthitic structure of orthoclase cryptoperthite are given.
