Why is it hard to obtain some pure elements?

Question

Zirconium and hafium occur together in nature. It is very difficult to obtain the pure elements. Can anybody explain to me why? I didn't understand my teacher and he used the example above.

Answer 1

Well the reason it is so hard to obtain those pure elements is basically stability. Every atom ,but the Noble gases, wants an octet, 8, valence electrons. So these atoms bond with other atoms of other elements, rendering them as impure, to have that octet.

I.E:They as in Zirconium and Hafium would rather be bonded together than pure. Though there are ways to pull the bonds apart.
For example is the separation of hydrogen and Oxygen when a current is pased through H2O, water.

Answer 2

Their chemical properties are so similar that they respond the same to chemical separation techniques. Special, usually seperation chromatography, methods are needed. They are time consuming and expensive.