Fancy a punt on praseodymium? The world of commodities investing has taken a radical romp across the periodic table. Once mostly limited to Au, Ag, Cu, Pt and various combinations of H and C, the usefulness of dozens of other elements in modern technology has spurred interest in funds that track producers or, when possible, hold stockpiles of rare substances.

The boom has shed light on some arcane markets for which, in some cases, there were only a handful of buyers and sellers globally. For more thinly traded ores, it is hard to tell if the arrival of investors was a reaction to perceived rarity or a contributing cause of it.

Investors can now not only take a flyer on physical palladium – a precious metal critical for pollution control that hardly any layman would be able to identify – but they can buy an exchange traded note that returns double the inverse of its daily performance. It is a stretch to call such innovations necessary or useful. In any case, they are not for the faint of heart. Exchange traded funds tracking producers of rare earth elements, lithium and uranium are down by 33 per cent, 37 per cent and 60 per?cent?respectively?this?year.