Visual detection of crystallographic orientations of fcc single crystals

A simple method to single out, with the naked eye, the position of several crystallographic orientations of a face-centered cubic metal, such as silver or gold, is described. The method is based on the observation that the preferential etching corresponding to some crystallographic orientations causes the formation of well-defined geometrical figures, such as triangles, squares, and circles. A number of faces are easily identified, since on a globeshaped single crystal the different geometrical figures recur on its surface according to the rules of the face-centered cubic system.