Is europium (Eu) heavy or light rare earth elements?

Many minerals contain europium Europium is associated with the other rare earth elements and is therefore mined together with them. it is lighter than iron its density =5.264 gm/cm^3 and the density of iron =7.835 gm/cm^3 Relative to most other elements, commercial applications for europium are few and rather specialized. read more

Commonly, rare-earth elements with atomic numbers 57 to 61 are classified as light and those with atomic numbers greater than 62 (corresponding to europium) are classified as heavy-rare earth elements. read more

Only 0.2% of the rare-earth element content is europium. The second large source for rare-earth elements between 1965 and its closure in the late 1990s was the Mountain Pass rare earth mine. The bastnäsite mined there is especially rich in the light rare-earth elements (La-Gd, Sc, and Y) and contains only 0.1% of europium. read more