Neodymium

In nature, neodymium is found in the Earth's crust, 24-40 ppm, in minerals such as monazite, bastnaesite, gadolinite and cerite, of which the first two are the commercially important sources [4]. The isotopes found in nature are ¹⁴²Nd (27.13 %, stable), ¹⁴³Nd (12.18 %, stable), ¹⁴⁴Nd (23.80 %, T_½ = 2.1 · 10¹⁵ years), ¹⁴⁵Nd (8.30 %, stable), ¹⁴⁶Nd (17.19 %, stable), ¹⁴⁸Nd (5.76 %, stable) and ¹⁵⁰Nd (5.64 %, stable) [4].

In pure solid form, neodymium exist in the following forms:
α-form: hexagonal crystal at < 868 °C [4]
β-form: body-centered cubic crystal at > 868 °C [4]