Scandium

Scandium was discovered in 1879 and is an extremely soft metal. The substance isn't extremely dense — it's just around three times as dense as water — yet it's found in over 800 minerals all over the world. Scandium is the 50th most abundant element on the planet, yet it's still uncommon enough to command a high premium. This metal will set you back about $270 per gram, or $122,500 per pound which takes the last place on this list of the most expensive elements in the world.

Scandium is found in most rare-earth and uranium combination deposits, although it is only recovered from these ores in a few mines across the world. The favorable benefits of scandium on aluminum alloys were found in the 1970s, and its usage in such alloys remains its only important application. The annual global commerce in scandium oxide is 15–20 tonnes. Surprisingly, despite its scarcity on Earth, scandium appears to be plentiful in space. The metal looks to be the 23rd most prevalent element in the Sun, while exact amounts throughout the galaxy are unknown.

Estimated Value: $270 per gram