The two polymorphs of are hexagonal and tetragonal.
Hexagonal has the same structure quartz , with germanium having coordination number . Tetragonal (The mineral argutite) has the notile-like structure seen in stishovite. Germanium in this motif has coordination number 6.
is a chemical analogue of . It is, to some extent a structural analogue, as the low and high-pressure short-range order (tetrahedral and octahedral) is the same. However, a number of differences exist. The phase diagram, and all three phases (crystalline, glass, liquid) have an increased sensitivity to pressure, undergoing pressure induced changes at much lower pressures than their equivalent analogues.