Hytritium

From Memory Alpha, the free Star Trek reference

Hytritium is the only compound able to neutralize tricyanate contaminations. It is highly unstable, expensive to produce, and too dangerous to deliver by transporter, so many traders stopped buying and selling it. Fortunately, Zibalian trader Kivas Fajo was in possession of a quantity of the substance when the USS Enterprise-D required it to clean the water table of the planet Beta Agni II in 2366. (TNG: "The Most Toys")