The determination of the orientation of section planes of meteoritic irons

Abstract

The Widmanstetter figures on a general plane section of a meteoritic iron of the octahedrite class consist of kamacite bands running in four directions, the traces of the four planes of the octahedron, while tessellated octahedrites show three more sets of bands, the traces of the cube planes. The angles which these bands make with one another give data which are in principle sufficient to define the crystallographic axes of the iron, but in practice there does not appear to be any simple direct method of effecting this definition. In the following, two simpler cases are first discussed, followed by a method for the general case somewhat shorter than any published method I am aware of, and by methods for orientation from the Neumann lines and from inclusions.