El Chino Copper Mine
El Chino CopperMine
Location: Santa Rita, New Mexico, United States.
Products: Copper Deposit.
Ore Type: Porphyry copper deposit with adjacent copper skarn deposits.
Host rocks: The predominant oxide copper mineral is chrysocolla. Chalcocite is the most important secondary copper sulfide mineral, and chalcopyrite and molybdenite the dominant primary sulfides.
Geological setting: The Cobre Mountains are composed of Proterozoic metamorphic and igneous rocks covered by about 3800 to 4800 feet of Paleozoic to Mesozoic sedimentary rocks. Cretaceous diorite to quartz diorite sills subsequently intruded these older rocks. Shortly thereafter, mafic to intermediate composition dikes and other intrusive bodies were emplaced and 2000 feet of intermediate composition lavas and breccias were erupted onto the surface. Next, the large granodioritic plutons at Chino and at Hanover-Fierro to the north were intruded. The last stage of intrusive activity in this area was the emplacement of rhyolitic dikes. The multiple intrusions locally domed and folded the older Paleozoic and Cretaceous strata.
Mineralization: Porphyry copper deposit are low-grade (<0.8%) disseminated deposits of copper found in and around small intrusive bodies composed of porhyritic diorite, granodiorite, monzonite or quartz monzonite (McLemore, 2008). The small plutons (also called stocks) are often shallowly emplaced at depth within 1 to 6 km of the earth's surface. The copper occurs within breccia or in networks of fractures, both in the porphyritic intrusion and in the adjoining country rocks.