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 Hard Rock Video), and Marilyn Manson's output with Richard Kern and Floria Sigismondi. NIN later collaborated with Bill Viola for live accompaniment. Trent Reznor also produced the soundtracks for the films "Natural Born Killers" and "Lost Highway", and served as "musical consultant" for "Man on Fire". Rob Zombie has directed three films. As of 2009, Marilyn Manson is in the process of directing "". Other films that have included prominent contributions from industrial metal artists include "The Crow", "Johnny Mnemonic", "Spawn", "The Matrix", "Blair Witch" and "A.I. Artificial Intelligence". Its emphasis on transgressive themes has made a few industrial metal