Speculum metal metal mixtures usually contain two parts copper to one part tin along with a small amount of arsenic, although there are other mixtures containing silver, lead, or zinc. The knowledge of making very hard white high luster metal out of bronze-type high-tin alloys may date back more than 2000 years in China although it could also be an invention of western civilizations. Such metals were used in sculpture and to make more effective mirrors than the more common yellow easily tarnishing bronze mirrors. In that era mirrors of speculum metal, or any precious metal, were rare and only owned by
Industrial metal were initially influenced by the Earache roster (namely Godflesh, Napalm Death and Bolt Thrower). The German band Oomph! after their second album Sperm started to play industrial metal combined with elements of death metal and groove metal until the album Plastik. Sepultura singer Max Cavalera's Nailbomb, a collaboration with Alex Newport, also practiced a combination of extreme metal and industrial production techniques. A lesser-known example of industrial death metal is Meathook Seed, made up of members of Napalm Death and the Florida death metal group Obituary. An industrial music fan, Obituary guitarist Trevor Peres suggested drum machines for "The End