Lutetium

In nature, lutetium is found in the Earth's crust, 0.75-0.8 ppm, in minerals such as xenotime, gadolinite and other rare earth minerals [4]. The isotopes found in nature are ¹⁷⁵Lu (97.4 %, stable) and ¹⁷⁶Lu (2.59 %, T_½ = 3.59 · 10¹⁰ years).

In pure form it is found in one crystalline form, hexagonal close-packed [4].