A deposit thought to have been formed at a depth ranging from 4,000 to 12,000 ft (1.2 to 3.7 km) below the surface and at a temperature between 175 degrees C and 300 degrees C. Such a deposit may take the form of a fissure vein, a series of parallel fissures called a sheeted zone, a replacement of the wall rock of fissures, or a large disseminated deposit. Much of the gold, silver, copper, lead, and zinc of the Western United States comes from these deposits.