Well my good fellow, there are different kinds of earthly metals that possess natural magnetic properties (Neodymium being an example). To answer the "can it melt?" question is to say: yes, it can melt, though each metal has their own melting point. To answer the "what happens to the magnetically if it does" goes in the field of particle science: usually electrons orbit around the nucleus, allowing it to behave like normal objects, however if electrons were to flow in a specific direction (northerly or southerly) it turns the object into a magnet. If you increase the temperature on the said magnet: the electrons would return to their natural orbit, for heat stimulates negative energy (electrons) causing the said magnet to lose it's magnetic properties.