Ytterbium

In nature, ytterbium is found in the Earth's crust, 2.66-3.1 ppm, in minerals such as xenotime, yttebite (gadolinite) and monazite [4]. The isotopes found in nature are ¹⁶⁸Yb (0.13 %, stable), ¹⁷⁰Yb (3.05 %, stable), ¹⁷¹Yb (14.3 %, stable), ¹⁷²Yb (21.9 %, stable), ¹⁷³Yb (16.12 %, stable), ¹⁷⁴Yb (31.8 %, stable) and ¹⁷⁶Yb (12.7 %, stable) [4].

In pure form ytterbium is found in two crystalline forms, face-centered cubic α-form, which transforms into a body-centered cubic β-form > 798 °C [4].