Combinations of holohedral tetragonal forms are shown in figs. 47-49;
fig. 48 is a combination of a bipyramid of the first order with one of
the second order and the prism of the first order; fig. 49 a
combination of a bipyramid of the first order with a ditetragonal
bipyramid and the prism of the second order. Compare also figs. 87 and
88.
Examples of substances which crystallize in this class are
cassiterite, rutile, anatase, zircon, thorite, vesuvianite,
apophyllite, phosgenite, also boron, tin, mercuric iodide.