Role of Spirals in the Growth of Prism Faces of Cultured Quartz

Abstract

A detailed study is made of surface structures of over four-hundred prism faces of cultured quartz. Growth spirals observed are illustrated. They have been examined with the help of a phase contrast microscope. Density of screw dislocations is found to vary between wide limits, being of the order of 104 cm−2 in most of the crowded regions. The role of spirals in the development of prism faces is discussed. Different types of interactions of spirals are illustrated. The origin of the formation of the spirals is also discussed. It is shown that the edges of the growth layers on the steeper sides of spiral growth pyramids constitute striations inclined at 45° to the edge between m(101̄0) and R(101̄1) faces.