Magnetic anisotropy of naturally occurring substances. I. Mother of pearl

Abstract

The magnetic anisotropies of the nacre of Turbo, Haliotis, M. margaratifera, Mytilus viridis and Nautilus pompilius, respectively, have been determined. The observations indicated that the c-axes of the aragonite crystals are in every case normal to the elementary laminæ. A random orientation of the a and b axes in Turbo and Haliotis, and a preferred orientation, with the a-axes approximately along the line of growth for M. margaratifera and Mytilus viridis, are tentatively suggested. A quasi-crystalline structure for conchyolin is suspected. The absolute susceptibilities of the shells have also been determined.