Brass than in brass produced by cementation. These may be "natural alloys" manufactured by smelting zinc rich copper ores in redox conditions. Many have similar tin contents to contemporary bronze artefacts and it is possible that some copper-zinc alloys were accidental and perhaps not even distinguished from copper. However the large number of copper-zinc alloys now known suggests that at least some were deliberately manufactured and many have zinc contents of more than 12% wt which would have resulted in a distinctive golden color. By the 8th–7th century BC Assyrian cuneiform tablets mention the exploitation of the "copper of the mountains"
Industrial metal with the success of groups such as Nine Inch Nails. The industrial metal movement began to fade in the latter half of the 1990s. Though electric guitars had been used by industrial artists since the early days of the genre, archetypal industrial groups such as Throbbing Gristle displayed a strong anti-rock stance. British post-punk band Killing Joke pioneered the crossing over between styles, and was an influence on major acts associated with industrial metal such as Ministry, Godflesh, and Nine Inch Nails. Another pioneer industrial rock group, Big Black, also impacted some later groups. By the late 1980s industrial and