Ytterbium is another metal destined to remain obscurity for the foreseeable future, silently filling minor industrial roles along with all the other elements in the lanthanide series of rare earth metals.

These Yibbies, as we've affectionately nicknamed the element at our office here, are made from triple-nine pure ytterbium metal and mark, so far as we know, the first time a density cube has been made of this material and offered for sale.

Weight of each 10mm cube is 6.7±0.5g.