On the lanthanides row of the periodic table element Lu sits at the far end both in a literal and symbolic sense. It is easily the rarest and most expensive rare earth metal (unless we count scandium). Its richest commercial ore, monazite, has a yield of just 0.0001%. Given its density of nearly 10 grams per cubic centimeter this means that it took 100 kilograms of ore to make just one of these little cubes!

Rarity and expense combine to leave lutetium as one of the most obscure and least commercially useful of all the stable metals. It does, however, make for one heck of a conversation piece!

Weight for the 10mm cube is 10.1±0.05g.