Rio Tinto (thru Resolution Corp) had purchased the assets of Magma Copper, whose primary holding was a mine outside of Superior. After several years of core-drilling, they established the presence of an immense lode of high-grade copper ore (largest in the world, as I recall) still present on the property.
One catch: the ore was something like 15,000 feet underground.
At the time, the eventual plan was to excavate a shaft, with galleries, blow up the roof to collapse the ore. And, because of the excessive heat at those depths, mine it with robots. The heat was also considered a benefit, since the ore would be partially refined by the conditions before it was brought to the surface.
Is this, I wonder, the fruition of this ambitious plan?
Rio Tinto Copper Fact Sheet
http://www.riotinto.com/documents/ReportsPublications/corpPub_Copper.pdf
Page 8
~6,500 ft deep, no robots required.
Resolution Copper
The Resolution Copper project is situated in Superior,
Arizona, US, in the area of the depleted Magma Copper
mine. Rio Tinto has a 55 per cent share in the project,
in partnership with BHP Billiton. The pre-feasibility
study is currently underway.
Exploration from 2001 to 2003 suggests that a large,
world class copper resource exists more than 2,000 metres
below surface. Pre feasibility studies are expected to be
completed by 2013 with production at the new mine
expected to start by 2020, eventually ramping up to
500,000 tonnes per annum of copper.
- - - - - - - -
In March 2010 the company reported an increased Inferred Resource of 1.624 billion tonnes at a grade of 1.47% Cu and 0.037% Mo.
http://www.resolutioncopper.com/res/whoweare/1.html#footnote
Which results in ~24 million metric tonnes or ~26 million US short tons.
The Chuquicamata mine in Chile is certainly larger, as are a few others. It is no doubt a world class mine and greatly valuable to us if it actually goes into production.
For comparison, the link below discusses some of the challenges in the Western Deep Levels gold mine, 12,200 feet below the surface.