Thorium is a dense, radioactive metal that is widely dispersed across the earth’s crust and found as a trace in many minerals. It is especially abundant in those that yield rare earth metals which then becomes both its primary ore and a headache for the refineries only interested in the rare earths as then the radioactive trace byproducts need to be dealt with.

The radioactivity of thorium itself is so slight as to barely register even on sensitive instruments. Indeed, over half of the thorium that was created in the Big Bang has yet to decay into other elements. Ironically, one of thorium’s few uses has been as radioactive shielding! Despite its largely benign nature the tiny portion of it that does decay happens to yield radium which in turn decays into radon gas. As the gas is heavy it tends to pool in unventilated areas and increases the risk of cancer to those exposed to its presence. For this reason - and the fact that isolating the metal is expensive in its own right - it has been almost entirely ignored by commercial metallurgists; explaining why it is so difficult to find even by dedicated collectors today.