Porphyry copper deposit 3049753 219018344 2008-06-13T05:28:26Z SharperLight 7301205 added Australian locality '''Porphyry copper deposits''' are [[copper]] [[ore]]bodies which are associated with [[porphyry_(geology)|porphyritic]] [[intrusive]] rocks. The ore occurs as disseminations along hairline fractures as well as within larger veins, which often form a [[stockwork]]. The orebodies typically contain between 0.4 and 1 % [[copper]] with smaller amounts of other metals such as [[molybdenum]], [[silver]] and [[gold]]. They are formed when large quantities of [[hydrothermal]] solutions carrying small quantities of metals pass through fractured rock within and around the intrusive and deposit the metals. Porphyry copper deposits are the largest source of copper, and are found in North and South America, Europe, Asia, and Pacific islands. None are documented in Africa. The largest examples are found in the [[Andes]] in [[South America]]. ==Characteristics== Characteristics of porphyry copper deposits include: *The orebodies are associated with multiple intrusions and [[Dike (geology)|dikes]] of [[diorite]] to [[quartz monzonite]] composition with porphyritic textures. *[[Breccia]] zones with angular or locally rounded fragments are commonly associated with the intrusives. The [[sulfide]] mineralization typically occurs between or within fragments. *The deposits typically have an outer [[epidote]] - [[chlorite]] mineral alteration zone. *A [[quartz]] - [[sericite]] alteration zone typically occurs closer to the center and may overprint. *A central ''potassic'' zone of secondary [[biotite]] and [[orthoclase]] alteration is commonly associated with most of the ore. *Fractures are often filled or coated by sulfides, or by [[quartz veins]] with sulfides. Closely spaced fractures of several orientations are usually associated with the highest grade ore. Porphyry copper deposits are typically mined by [[Open-pit mining|open-pit]] methods. ==Examples of porphyry copper deposits== * [[La Caridad]], [[Sonora]], Mexico * Ok Tedi, [[Papua New Guinea]] * Dizon, [[Philippines]] ===Chile=== * Andina * Cerro Colorado * [[Chuquicamata]] * Collahuasi * [[Escondida]] * El Abra * [[El Teniente]] * Los Bronces * Los Pelambres * Quebrada Blanca * Radomiro Tomic * Salvador * Zaldivar ===Peru=== * [[Toquepala]] * [[Cuajone]] * [[Cerro Verde]] ===United States=== * [[Ajo, Arizona]] * [[Bagdad, Arizona]] * [[Lavender Pit]], [[Bisbee, Arizona]] * [[Morenci, Arizona]] * [[Pebble Mine]], [[Alaska]] * [[Safford Mine]], [[Safford, Arizona]] * [[San Manuel, Arizona]] * [[Sierrita, Arizona]] * [[El Chino Mine|El Chino]], [[Santa Rita, New Mexico]] * [[Ely, Nevada]] * [[Bingham Canyon Mine]], [[Utah]] * [[Ray Mine, Arizona]] ===Australia=== * [[Callawa, Western Australia]] - location being confirmed as porphyry by drilling mid 2008 at lat -20.684398 lon 120.439596 ==Porphyry-type ore deposits for metals other than copper== Copper is not the only metal that occurs in porphyry deposits. There are also porphyry ore deposits mined primarily for [[molybdenum]], many of which contain very little copper. Examples of porphyry molybdenum deposits are the [[Climax, Colorado|Climax]], Urad, and Henderson deposits in central [[Colorado]], and the [[Questa, New Mexico|Questa]] deposit in northern [[New Mexico]]. The US Geological Survey has classed the [[Chorolque]] and [[Catavi]] tin deposits in [[Bolivia]] as ''porphyry tin deposits''.<ref>Bruce L. Reed (1986) ''Descriptive model of porphyry Sn'', in ''Mineral Deposit Models'', US Geological Survey Bulletin 1693, p.108.</ref> Some porphyry copper deposits in oceanic crust environments, such as those in the [[Philippines]], [[Indonesia]], and [[Papua New Guinea]], are sufficiently rich in gold that they are called copper-gold porphyry deposits.<ref>R. L. Andrew (1995) ''Porphyry copper-gold deposits of the southwest Pacific'', Mining Engineering, 1/1995, p.33-38.</ref> ==References== <references/> {{geology-stub}} [[Category:Economic geology]] [[Category:Copper]] [[de:Porphyrische Kupferlagerstätte]]