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 Industrial metal Industrial metal (also known as industro-metal, industrial–metal, metallic industrial, cyber-metal etc.) is the fusion of heavy metal music and industrial music, typically employing repeating metal guitar riffs, sampling, synthesizer or sequencer lines, and distorted vocals. Prominent industrial metal acts include Ministry, Godflesh, KMFDM and Nine Inch Nails. Industrial metal developed in the late 1980s, as industrial and metal began to fuse into a common genre. In the early years of the 21st century, groups from the black metal scene began to incorporate elements of industrial music. Industrial metal did well in the early 1990s, particularly in North America,