Читать книгу Earth Materials - John O'Brien - Страница 95

The symmetry of three‐dimensional crystals can be quite complex. Understanding symmetry in two dimensions provides an excellent basis for understanding the increased complexity that characterizes three‐dimensional symmetries. It also provides a basis for learning to visualize planes of constituents within three‐dimensional crystals. Being able to visualize and reference lattice planes is of the utmost importance in describing cleavage and crystal faces and in the identification of minerals by X‐ray diffraction methods.