In this case brother, total scale of these monsters aside, the ore content is around 1.2% Cu & 0.5 g/t Au
So I don't see this being a hell of a lot different once all dilution etc is factored in, though there is a super leached oxide zone we know of and hopefully a supergene zone at depth as well.
The only thing I'm curious on is the total tonnage? Because it almost reads as if each Porph is a 500Mt potential..
Exciting prospect if that is the case whereby an area of 500m x 500m x 800m depth = 200'000'000 cubic metres of ore.
Multiply that by an av specific gravity of say 2.5 for the type of host lithology and you've got 500Mt.
So yeah, I'm keen to see how big these IP foot prints are, for sure.. Honestly though, at our current MC we are undervalued for the 0-50m of gold oxide (100k+ Oz Au) sitting on top of the bloody thing let alone anything else..
Just sayin... ;-) H8tey
Grasberg geology
The mine stands at the collision of the Indo-Australian and the Pacific tectonic plates. Two distinct phases of intrusion have led to the production of nested coaxial porphyry ore bodies and sulphide-rich skarn at the margins, while sedimentary strata include Eocene clastic carbonate limestone with siltstones and sandstones near the base.
The Dalam Diatreme (DD) forms the first intrusive stage, being highly fragmental and characterised by clasts and a matrix of dioritic composition.
Mineralisation is largely disseminated and chalcopyrite dominant, having average grades of 1.2% copper and 0.5g/t gold.
The second intrusive stage, the Main Grasberg Stock (MG), is composed of non-fragmental, porphyritic monzodiorites, forming a quartz-magnetite dilational stockwork with veinlet-controlled copper-gold mineralisation. This is a high-grade resource, with averages of 1.5% copper and 2g/t gold.Escondida geology and ore reserves
Escondida is related geologically to three porphyry bodies intruded along the major Chilean west fissure fault system. Primary hydrothermal sulphide ore grades at between 0.2% and 1% copper.
Subsequent weathering and uplifting created a barren, leached cap, up to 180m thick, over a high-grade supergene-enriched ore, both overlying the primary sulphides. Primary sulphide mineralisation includes pyrite, chalcopyrite and bornite, with covellite and chalcocite in the enriched zone.
The combined proven and probable ore reserves of Escondida and Escondida Norte as of mid-2004 were: 2,018 million tonnes (mt) of copper sulphide ore at 1.24% total copper; 1,701mt of low-grade copper sulphide ore at 0.55% total copper; and 290mt of copper oxide ore at 0.73% acid-soluble copper.
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