What is Klorium?
See pharvecloft explanation below my post. His explanation was so much better, I could not help but delete mine.
Klorium is the unofficial name for element 117 in the periodic table. Being a Halogen it is fairly reactive; think of Chlorine and Fluorine. Being element 117, it is also highly radioactive. So, when you find this stuff, extreme caution is required during its handling. Because it is both chemically reactive and radioactive, it is a potent substance for your crafting endeavors. Allowing one to make truly powerful implements.
As always with the bleeding edge of science, discoveries such as this may be overhyped on the web.