Encouraged by positive drill results,
Since drilling began, in July, Summo has drilled 33 holes (4,800 metres), results from which will be used to form a new resource model.
Based on results of previous work, the resource is believed to be 68 million tonnes grading 0.44% copper and 0.41% zinc, with a stripping ratio of 0.5-to-1. The capital cost, according to a scoping study, is about US$112 million.
The prefeasibility, scheduled for completion in early 2001, is expected to include a higher resource, as well as higher zinc grades of as much as 0.8% (core from the previous drilling was not analyzed for zinc).
The recent drilling pushed the limits of the oxide deposit to the east and the west. The deposit measures more than 1,000 by 400 metres and is only 75 metres thick, accounting for the low stripping ratio.
Mineralization consists of malachite, chrysocolla, tenorite, smithsonite, hemimorphite and hydrozincite, all of which is hosted in what is believed to be a roof pendant within a weakly altered monzonite.
Leach tests on drill cuttings will be performed by Arizona-based METCON Laboratories. In the meantime, Summo has sent zinc-bearing leach solution to a laboratory in Spain to determine the most economical method for electrowinning the zinc from the solution.
Based on the current resource, the company believes it can produce 55 million lbs. of copper cathode and 42 million lbs. of zinc ingots annually for 10 years. Cash operating costs could drop to below US40 per lb. copper, including higher zinc credits.
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