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Primary Copper and Aluminum
Published in Margaret E. Slade, An Econometric Model of the U.S. Copper and Aluminum Industries, 1984
The long-run elasticity of supply of U.S. primary copper, computed from III:5:9 (using the coefficients from the primary production equation in log-log form), is .21. Supply is very inelastic, even in the long-run. This small supply elasticity is very different from that computed by Fisher-Cootner-Baily (1972). FCB found supply to be fairly elastic in the long-run (ηℓ = 1.67). Because FCB used the traditional short-run supply-curve approach, the two results are not directly comparable. However, it is possible that the U.S. copper industry is now operating at a point where costs increase sharply as output expands. The last year of the data used for the FCB estimates was 1966. In the ten years between 1966 and 1976, there have been two important contributors to higher costs for capacity expansions in the domestic copper industry. First, in copper mining, most of the very large, high-quality porphyry-copper deposits have been fully developed. Because newly discovered deposits tend to be smaller, of lower grade, or more deeply buried, costs for new mines are higher than are costs for existing ones. And second, in copper smelting, new air-pollution-control regulations limiting emissions of sulfur dioxide (so2) and particulates have led to increased capital costs. Because new smelters have to meet New-Source Performance Standards, substantial price increases are required to bring new smelting capacity on line. Even though the econometric estimates of long-run supply elasticities may be fairly imprecise, with such a large difference between the two estimates, it seems reasonable to conclude that the long-run supply of copper in the U-S. is substantially less elastic now than it was ten years ago.
Resources and Processing
Published in C. K. Gupta, Extractive Metallurgy of Molybdenum, 2017
The term “porphyry copper” originated in the U.S. for describing large copper deposits of low grade in which copper-bearing minerals occur as grains or disseminated veinlets. In copper porphyries, molybdenite content ranges from about 0.015 to 0.1% as a maximum limit. Some typical examples of availability of porphyry copper deposits are shown in Table 2.
Partial sub-pixel and pixel-based alteration mapping of porphyry system using ASTER data: regional case study in western Yazd, Iran
Published in International Journal of Image and Data Fusion, 2019
Amir Taghavi, Mohammad Maanijou, David Lentz, Ali-Asghar Sepahi
Subduction of Neo-Tethys beneath the central Iran continental margin and collision of the Afro-Arabia plate with the Iranian plateau lead to generation of a NW-SE trending volcano-plutonic belt called Sahand-Bazman (SBMB) or Urumieh-Dokhtar Magmatic Belt (UDMB). In general, Neo-Tethyan subduction from the Jurassic to Tertiary is considered as the key process generating arc magmatism in the UDMB (e.g. Berberian and King 1981, Alavi 1994, Omrani et al. 2008, Verdel et al. 2011), and, also in the Sanandaj-Sirjan Zone (SSZ) (e.g. Mohajjel et al. 2003, Baharifar et al. 2004, Ghasemi and Talbot 2006, Arvin et al. 2007, Aghazadeh et al. 2011, Aliani et al. 2015). The closure of the Neo-Tethyan ocean and eventually plate collision and crustal thickening during the Tertiary period yielded a fertile UDMB with clustered PCDs a few tens of kilometers wide (e.g. McInnes et al. 2003, Agard et al. 2005, Shafiei et al. 2009, Dargahi et al. 2010, Richards et al. 2012) and ca.1800 km in length. World-class porphyry copper mines (e.g. Sar-Cheshmeh and Sungun) have long been recognised within the UMDB and have been studied by many geologist researchers for over forty years (Dimitrijevic 1973, Waterman and Hamilton 1975, Jung et al. 1976, Forster 1978, Berberian et al. 1982, Hooper et al. 1994, Jankovic 1997, Mohajjel et al. 2003, Shahbpour 2005, Ghasemi and Talbot 2006, Shahabpour 2007, Ahmadian et al. 2009, Boomeri et al. 2009, Shafiei et al. 2009, Hassanpour et al. 2010, Jamali et al. 2010).
Exsolution depth and migration pathways of mineralising fluids in porphyry systems – examples from the Yerington District, Nevada
Published in Applied Earth Science, 2019
L. C. Carter, B. J. Williamson, R. N. Armstrong, S. Tapster
Porphyry copper deposits provide around 75% of the world’s copper and are an important source of gold and other metals (Sillitoe 2010). One aspect of porphyry deposit models that is poorly understood is whether the mineralising fluids from which they form are derived from: (i) high-level copper-rich porphyry magmatic stocks; (ii) feeder chambers at mid-upper crustal levels; (iii) a lower crustal reservoir; or (iv) a combination of these in a transcrustal mush zone (e.g. Cashman et al. 2017). The high level porphyry stock is often assumed to be the fluid source as it is invariably mineralised and can usually be temporally and texturally linked to the mineralisation. It is unlikely, however, that enough fluid could be derived from such a limited volume of magma. It seems probable therefore that much of the fluid came from a deeper source, possibly 5–15 km, although how fluids are transported from such depths is poorly understood.