[AstralTraveller (David)]

Combine it with hydrogen and you have the strongest acid known. It is perhaps the only thing I am aware of that will dissolve silicates (possibly boiling anhydrous NaOH also works). For this reason it is used in geochemical research. It is also incredibly toxic and will kill you as soon as look at you. It is absorbed through the skin and causes organ failure. Direct contact with even a few mL is generally fatal. [Terry in the OSL lab etches mineral grains with HF in near darkness, the red light is so faint even an experienced astronomer would find it daunting. He can keep it.]

The discovery of fluorine is an interesting and tragic tale. Researchers often accidentally actually made HF and then unwittingly exposed themselves to it. There were several deaths. Also the HF attacks glass apparatus and so it wasn't until someone built a set of pure Pt apparatus that it was isolated.