Michigan Copper is almost unique among copper-mining areas, because the copper is found in the form of pure copper metal (native copper) instead of the copper oxides or sulfides that form the copper ore at almost every other copper-mining district. Within the state of Michigan, copper is found almost exclusively in the western portion of the Upper Peninsula, in an area known as the Copper Country. The Copper Country is highly unusual among copper-mining districts, because copper is predominantly found in the form of purecopper metal (native copper) rather than the copper oxides or copper sulfides that form the copper ore at almost every other copper-mining district. The copper deposits occur in rocks of Precambrian age, in a thick sequence of northwest-dipping sandstones, conglomerates, ash beds, and flood basalts associated with the Keweenawan Rift. Although native copper was the dominant ore mineral, chalcocite (copper sulfide) was sometimes present, and, especially in the Mohawk mine, copper arsenide minerals such as mohawkite and domeykite. Gangue minerals included calcite, quartz, epidote, chlorite, and variouszeolites. A number of copper mines also contained a notable amount of silver, both in native form and naturally alloyed with the copper.Halfbreed is the term for an ore sample that contains the pure copper and pure silver in the same piece of rock; it is only found in the native copper deposits of the Upper Peninsula of Michigan.The Michigan State Geologist Douglass Houghton (later to become mayor of Detroit) reported on the copper deposits in 1841, which quickly began a rush of prospectors. Mining took place along a belt that stretched about 100 miles southwest to northeast throughOntonagon, Houghton, and Keweenaw counties. Isle Royale, on the north side of Lake Superior, was extensively explored, and a smelter built, but no mining of any importance took place there. Some copper mineralization was found in Keweenawan rocks farther southwest in Douglas County, Wisconsin, but no successful mines were developed there. Copper mining in the Upper Peninsula boomed, and from 1845 until 1887 (when it was exceeded by Butte, Montana) the Michigan Copper Country was the nation's leading producer of copper. In most years from 1850 through 1881, Michigan produced more than three-quarters of the nation's copper, and in 1869 produced more than 95% of the country's copper. COPPER is a basic element (Cu) and is the eighth most abundant metal in the Earth's crust. It occurs as a native metal and in a some 160 compounds, some of which are azurite, malachite, chrysocolla, chalcopyrite and bornite. The alloys of copper are also important such as bronze, an alloy of tin and copper; and brass, an alloy of zinc and copper.Being malleable and ductile, copper is a good conductor of heat and electricity and has many industrial uses, among which are electric cables and wires, plumbing, heating, roofing and construction. The Egyptians are believed to be the first to create bronze, which ushered in the Bronze Age. Leading producers of copper are Chile, the U.S. and Indonesia. Three U.S. states are very rich in copper deposits: Arizona, New Mexico and Utah. Copper is mined in at least 63 countries, including Russia, Canada, Zambia, Poland, China, Uganda, Nicaragua, Australia and Mexico.