Tantalum (Ta) is a dark blue-gray metal that is very heavy, ductile and hard and has high corrosion resistance. Tantalum is especially resistant to chemicals at temperatures below 150 °C and can only be dissolved with hydrofluoric acid. It has the fourth-highest melting point of all metals and is able to form extremely thin and protective oxide layers for high-quality capacitors, making it an excellent material for lumps.