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 metal with industrial music in the late 1980s Pigface, formed by Martin Atkins and including Ministry drummer Bill Rieflin, emerged as an industrial metal collective of sorts, participating with many figures from the noise rock and industrial worlds. Nine Inch Nails, the "one-man-band" formed by Trent Reznor, brought the genre to mainstream audiences with albums such as the Grammy-winning "Broken" and the best-selling "The Downward Spiral", accompanied by their groundbreaking performance at Woodstock '94. The rivethead subculture also developed at this time, along with the so-called "coldwave" subgenre, which encompassed Chemlab, 16 Volt, and Acumen Nation. Some electro-industrial groups adopted