Zinc coated steel replaced the previous uncoated rust-prone sheet metal. Lower tunings are popular among rock and heavy metal bands. Mercury is a heavy, silvery-white liquid metal. Slayer is one of the most influential bands in heavy metal history. Mountain is one of the bands considered to be forerunners of heavy metal. They are often cited as pioneers of heavy metal music. Titanium alone is a strong, light metal. This behavior is similar to that of aluminium metal. Neither does silver, or any other precious metal or gem. Hardy is a fan of punk, metal and hardcore music. Tungsten has the lowest coefficient of thermal expansion of any pure metal. It must be concealed behind drywall, sheet metal, or concrete. See Forging for hot metal forming operations. He provided voices for multiple characters in the animated film "Heavy Metal" (1981). This prevents impurities from forming in the metal.