Germanium

In nature, germanium is found in the Earth's crust, 7 ppm [7]. The isotopes found in nature are ⁷⁰Ge (20.55 %, stable), ⁷²Ge (27.37 %, stable), ⁷³Ge (7.67 %, stable), ⁷⁴Ge (36.74 %, stable) and ⁷⁶Ge (7.67 %, stable) [6].

In pure solid form, germanium exist in a diamond cubic structure, when crystalline [4,7].