Finding Chuqui’s lost ore – Lowell on tackling world-class mystery – by Kip Keen (Mineweb.com – August 1, 2013)

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The massive Chuquicamata copper deposit has long been theorized to be missing ore, possibly faulted off to the south. Now exploration legend David Lowell is looking.

HALIFAX, NS (MINEWEB) – David Lowell, the famed octogenarian explorer credited with finding the Escondida copper deposit, among others, is now taking a crack at one of the world’s greatest exploration mysteries: finding lost – or believed to be lost – Chuquicamata copper ore. Forgive the superlative. For the known Chuquicamata copper-molybdenum deposit and mine in Chile, now owned by Codelco, is ranked by many as the greatest – or certainly one of the greatest – copper ore bodies in the world.

Chuquicamata, Chuqui for short, is big and, for its size, very high grade. A mid-2000s estimate tallied 2 billion tonnes @ 1.54 percent copper as having been mined. These days, a grade a third that is considered pretty normal – good even – for a large porphyry deposit like this. So Chuqui is abnormal. And many billion tonnes of ore remain at the known Chuqui deposit. As the massive Chuqui open pit wanes, Codelco aims to continue mining in a giant block cave mine it estimates will cost about $4.2 billion to build. The pit is reaching its limits, about 900 metres deep, and four kilometres long and three kilometres wide.

The Chuqui mystery is this: a fault, called the West Fault, cuts through the Chuqui ore body and appears to have moved a chunk – how much is not clear – of Chuqui ore elsewhere, where or exactly how far is uncertain. But most guesses, those made in a so far fruitless search for lost Chuqui ore, have put it somewhere about 15 to 20 kilometres to the south on a property that is known as the Ricardo project.

It’s a roughly 16,000 hectare property on the edge of the Chilean town of Calama that has stymied many before Lowell, who spoke about his pursuit of lost Chuqui ore with Mineweb on Wednesday. Since the theory that such lost ore existed was developed in the 1970s, a slew of majors, among others, have puzzled over the quest, mapping, sampling and, more than anything else, drilling away at the Ricardo property through which the all-important West Fault traverses.

All have come up empty handed. Superior Oil hit the ground between 1980 and 1982. Codelco was there in 1991 and 1992. Freeport came in the next two years and Inco, likewise, the next two after that. Among majors Rio Tinto made the last and still unsuccessful attempt at finding Chuqui ore at Ricardo in the mid 2000s. In all 72 drillholes have been drilled, multiple geophysical surveys have been conducted and a fair amount of brain power and cash has been expended on the mystery of the lost Chuqui ore. To no avail.

Lowell would not, however, be considered a geological crackpot, flogging an idiotic exploration idea. He exists on the opposite end of the scale. Something of a legend, a porphyry expert, and wildly successful explorationist. Over the years he has made many of the more important copper discoveries in Latin America, prime among them Escondida. Unlike this author, he is not prone to superlatives.

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