Chapters Covered by Exam #1:

In Nesse, Introduction to Mineralogy
• Chapter 1 - definition of a mineral, History of Mineralogy
• Chapter 2 - Symmetry (re: p. 24-34 - Just familiarize yourself with the more basic crystal forms - the ones I emphasized in class.)
  • translational symmetry in one, two, and three dimensions, including plane lattices, space lattices and the unit cell
  • the Crystal Systems including the length and angular relationships between the crystallographic axes
  • point symmetry, including mirror planes, rotational axes, center of symmetry and rotoinversion axes - expect blocks and be prepared to identify all symmetry elements and assign them to their crystal systems
  • combining point symmetry and translational symmetry in two dimensions
  • crystal habit

Some examples of essay-type questions:

• Some potential definition terms: symmetry (point and translational), unit cell, plane lattice, unit mesh, primitive vs. centered meshes, crystal system, crystal class, Bravais Lattice, triclinic, monoclinic, orthorhombic, hexagonal, tetragonal, isometric/cubic, crystal form, crystal habit, center of symmetry, rotational axis, rotoinversion axis, glide plane, mirror plane, screw axis, twinning, etc.
• What symmetry operation is equivalent to a mirror plane? Which is equivalent to a three-fold rotoinversion? Identify the unit cell in a given pattern. Is the unit cell primitive, face-centered, or body-centered?
• Name the six crystal systems and state the relations of their crystallographic axes (lengths of axes and angles between axes) (The big table). Be able to recognize these from a crystal structure or wooden block.
• Draw the five distinct plane lattices. Indicate the relative lengths of the translation distances (a and b) and the angle which relates them (g). Draw a unit cell for each lattice. Which lattice has a centered unit cell?
• Given a wooden block (pick any one - or more): list all of the symmetry elements present and identify the crystal system (without the help of Table 2.2). Bonus points if you can identify the specific crystal class (point group) by Hermann-Mauguin notation and/or the crystal forms. Miller Indices? Yup!
• The Great Pyramid of Cheops in Egypt is an example of a square pyramid (triangular sides, square base). Given the idealized shape of an square pyramid, identify all symmetry elements present. To which crystal system would the Great Pyramid belong? Draw its crystallographic axes.