Gold

Not to be mistaken for Glod, as is often the case.

A precious metal which is highly sought after and in demand for use in economic transactions of all kinds and for its jewellery value. Twenty times denser than water, it dissolves in mercury, and is inert except in the presence of highly reactive halogen ions, as in Aqua Regia, (and probably Aqua Quirmis*) and cyanide....

OK then, how long could YOU sing about it? It's yellow, it goes ching, and you can buy things with it. About five seconds, I'd think.

Then you're evidently not a Dwarf, a race who can make a good old favourite last up to five hours. Of course Dwarfs don't really love gold, they just say they do to get it in bed.

Gold is said to be so boringly commonplace on the Counterweight Continent that it is cheaper than lead and fulfills many of the functions there for which lead is commonly used in the hubward Circle Sea regions.

A discussion of the economic importance of gold, and the reasons why everyone thinks it's important for the banks to have some in the cellar - when it can be proven that this doesn't really matter a damn - happens in Making Money, where the concept of the Gold Standard is practically tested and found wanting.**

Another sly reference which TP is alluding to here is the gift of the Elven Lady Galadriel to the dwarf Gimli, in Tolkien's The Lord of the Rings, where she blesses him and prophesies that "your hands shall flow with gold, and yet over you gold shall have no dominion." (LotR II, ch 8) Most Discworld Dwarfs would sacrifice limbs and firstborn children for the former, but be totally incapable of understanding the latter clause. "Of course gold is meant to have power over you, that's what the damn stuff's for!"

...* Aqua Regia is a 1:3 mixture of nitric and hydrochloric acid which is capable of dissolving gold. Aqua Quirmis, as described by Cheery Littlebottom, is quite possibly the Disc's equivalent of this potent brew which well deserves its Alchemists' Guild subtitle of Kysse Thyyne Eyebrowes Fare-thee-well - as well as any other inadvertently exposed tissue...

...** Ankh-Morpork has been debasing its currency for some time. Near the beginning of The Colour of Magic we learn that their "gold" coins are only one-third gold. Later on, Vetinari got it down to about the gold content of seawater, but it was a promise to pay One Dollar, the actual gold being kept in the vaults for safety. By Making Money, of course, the gold has gone altogether but no one notices.