pole of a face

Updated About encyclopedia.com content Print Article Share Article
views updated

pole of a face (face pole) The normal (line perpendicular) to a crystal face, and the point at which the normal intersects the plane of projection. In a stereographic projection of a crystal, the crystal is imagined to lie at the centre of a sphere and a pole of each face intersects the surface of the sphere at a point. These points are then projected to either the N. or S. pole of the sphere, on to the horizontal (equatorial) plane to produce an accurate, two-dimensional representation of the faces and interfacial angles of the crystal.