The Hillsboro district, in central New Mexico, is an example of the typical geologic style of the development of Laramide porphyry copper deposits in southwestern United States. Porphyry copper deposits form from hydrothermal fluids that come from a magmatic source, generally a volcano. The copper is concentrated first by magmatic-hydrothermal processes, then copper can be further concentrated by later supergene fluids, typically meteoric waters. Porphyry copper deposits typically are large deposits and are mined mostly by open pit methods and can have by-product production of gold, silver, molybdenum, and other metals. Other types of deposits, such as skarns and polymetallic veins can occur near the porphyry copper deposits. Much of the world's copper is produced from porphyry copper deposits.