context: Thorium dioxide is the highest melting point refractory metal among oxidized compounds (3390 ° C). Adding 0.8–1% of ThO2 to tungsten stabilizes the structure of the tungsten, which in turn improves the mechanical stability of the filament and thus withstands vibrations. When dissolving ThO2 in acid, the temperature rises to 500–600 ° C. Heating up to 600 ° C produces a different form of ThO2, which causes very high resistance to acidic materials. Small amounts of fluorinated ions catalyze the dissolution of thorium dioxide in acidic materials.
question: What is the heavy metal with the highest melting point?
answers.text: Thorium dioxide