I heated a chunk of indium to red heat. It initially melted, then seemed to solidify. In fact, the surface developed a skin of indium oxide which prevented the metal from dripping all over. After this skin was formed, there was no more oxidation. I can try heating a piece of thin indium foil and seeing whether it oxidizes more thoroughly. Here is what the indium looked like after heating. The indium is still soft and malleable under the coating.