The Coruna Copper Mines.
The Coruna Copper Company’s property, which covers an area of 2,540 acres—a tract of country more than six times as large as Hyde Park—is situated in the mining district of Santiago, and is connected with the railway, which is about eight miles distant, by a first-class road. The country in which the concession is situated, consists of a series of low rolling hills, and the character of the ore, so far as it has yet been explored by the prospecting operations, is very similar to that produced by the Rio Tinto and Tharsis Mines. It is a low grade copper ore, carrying on the average twenty-three per cent. of sulphur, and from two to three per cent. of copper. No attempt was made by the late owners to determine by a systematic series of borings the extent over which the mineral actually exists, or the depth and character of the ore; but the prospecting work already carried out by the English company, and the natural outcrops found at many points on the concession, place it, in the estimation of some mining experts, quite beyond doubt that the mass of mineral is one of the largest known, extending in one direction for over two miles, apparently without a break. This preliminary work has clearly proved the whole of the north-west quarter of the concession; and taking the outcrops into account, one-half of the whole ground is assumed to contain mineral. Three shafts and nine trenches are being sunk, and numerous outcrops have also been located on the concession. The original estimate of the quantity of mineral was 50,000,000 cubic metres, equal in round figures to 250,000,000 tons. The most recent assays indicate a mean of three per cent. copper in the ore. The prospecting work has in every instance proved the accuracy of original estimates as to the value of the property, as well as the correctness of the opinion, that a very large output could be obtained with practically none of the unproductive development work required in most mining enterprises. It was recommended that mining operations should be chiefly “open-cut,” and of the simplest character, the exceptionally favourable conditions under which the ore exists rendering operations an extremely easy and inexpensive matter. The property is being opened up on these lines, and it is considered there will be no difficulty in supplying the concentrating works with 1,000, 2,000, or even 3,000 tons per day, all obtained from open cutting.