Californium - $27 Million / Gram

Californium is yet another rare and very expensive chemical substance. It is a radioactive metallic chemical element which can be found in periodic table, with atomic number 98. it was first made in 1950 by combining curium and alpha particles. A gram of Californium costs about $27 million. Californium doesn't exist on earth naturally. It can only be made.

This Post Belongs To 15 Most Rare and Expensive Materials In The World