COPPER-MINING IN THE COLONIES.

Otago Daily Times, Issue 5205, 23 October 1878, Page 3

COPPER-MINING IN THE COLONIES.

(From the New Zealander.)

Now that the production of copper .promises to be added to the number of our staple industries, and as a general auisconception, or at least a variety of opmions are known to prevail as to the •percentage of copper in the ore that is necessary to render payable its production, it may bo of interest to the public generally, if a few returns are tabulated, and some information of a non-scientific character given in our columns, as to •what pr"»ros3 is being made in the -colonies of New South Wales and Queensland in connection with thi3 industry, which we hope to see flourishing and largely developed in New Zealand. There is a difficulty in obtaining completo information as to the progress or the prosperity of this branch of mining in Australia ; but it should be borne in mind that the figures here given are correct, being collected from directors' reports, and the annual report of the Department of .Mines, New South Wales, for the year 1878. While lacking, however, such ■ complete information as could only bo ■ collected by a troublesome amount of research, tho details in our possession are pregnant with interest, and will, it is to ibe hoped, have the effect of stimulating enterprise. The value of the copper exported from New Soutli Wales from 1858 to 1877 in--elusive was £1,891,927 ; the weight, ■24 217 tons. The increase of the export jjaa been gradual with the exception of 1874 when tho value of tho export was ~-£325,140, against £324,226 last year— but tho difference in value in the earlier period arose from the difference in the price of the metal to that in 1877; the relative tonnage being 3038 in 1874, and 4153 tons in 1877, and there were at this date large quantities in hand. Tho price realised during tlie whole period in round figures may bo put down at £80 per ton. -ITroiu Professor Liversidge's report, we learn that oxidised ores are raised, varying from <),48 to 49.27 in percentage, giving an average from eleven localities •of 21.25 per cent. Of pyritous copper ores, tho percentage ranged from 3.07 to 27.49, averaging from the twelve mines ..cited 10.45 per cent. Under tho head •of auriferous and agentiferou3 copper

ores, we learn that "on examining some of the copper ore 3 for the precious metals, it was found that several of them contained really considerable quantities of both gold and silver;" and ''there is no reason why most of these ores should not be successfully treated for the extraction of the precious metals which they contain." Threa instances will suffice to show the proportion in which the precious metals exist in combination with the copper, but it must be the remembered that they are the richest among the 110 mines catalogued. Green carbonate of copper, Mitchell's Creek, metallic copper, 12.57 percent. ; silver, 13 oz. 13 dwts. per ton gold, loz 2 dwts 20 grs per ton. Green carbonate of copper same locality. Metallic copper 9.48 per cent.—silver, 9 oz 9 dwts per ton ; gold 4oz 10 dwts 18 grs per ton. Rod oxide of copper, same locality. Metallic copper 25.79 per cent. —silver, 1 oz 11 dwt per ton ; gold, 14 oz 10 dwts 0 grs per ton. One would be induced to imagine that were the D'Urville copper properly tested the precious metals may be found in combination therewith, the locality contiguous being auriferous. The report remarks—"Although we commenced to raise copper ore twenty years back, it may fairly be said in view of the extent of our deposits that we have scarcely as yet begun to tap our copper lodes. The reason that our copper lodes have not been more extensively worked is probably due to the fact that in most cases the cost of carrying the ore in a ran state to the smelting works has been sc great as to deter miners who did not possess the capital necessary to erect furnaces, or do not possess the skill necessary to enable them to reduce the ore to regulus, from embarking in this branch of mining." Tlie Mining Registrar of the Bathurst division communicates this interesting fact—" This important fact has been established, that payable sulphurets of copper exist underneath the surface deposit of carbonates." This had not been before demonstrated.

The report of the directors of the New Peak Down Copper Mining Company, situated in Queensland, ha 3 been recently published, and the information it contains must be of interest to all who wish to see the D'Urville Company a success. The mine is a new one, and the report deals only with the operations extending over six months—a third of the time being taken up in preliminary works before smelting operations could be commenced. In the balance-sheet for the half-year credit is taken for 224 tons of copper, in transit, valued at £G0 per ton at the mine, making a total of £13,447, to whicli is added money paid for insurance, carriage, commission, &c, £1506 ; then follows copper in stock, 12 tons, £722 ; ores at grass—estimated to contain 10 per cent, of copper—£73o2 ; less cost l of reducing, £2550 —£4730, making a total net value of copper in transit and ore at grass of £20,421. The cash paid for the minG, stores on tho ground, as per list, firewood, and other items, make up a grand total of £24,806 on the credit sido of the account. On the other side is placed the subscribed capital, £10,000, of which £9888 has been paid up; advances from banks, £9387 ; bills payable, and sundry creditors, £2679 ; leaving a balance to profit and loss of £2910, being a return at tho rate of about £6000 per annum on the £10,000 capital invested. The Company laboured under the disadvantage of a dearth of firewood, an event not likely to happen in the history of our mine in the Strait. A large proportion of the sulphurets raised only averaged 8 per cent, The lode, the mining manager states, varies in width from a few inches up to five feet, and in ono portion of the workings contains sulphurets averaging about 7 per cent.— tho sulphurets being very valuable for reducing tho more refractory ores. The smelting manager states that the consumption of wood has been equal to 3 tons Bcwt, and 2qrs. per ton of oro smelted, or 31 tons per ton of copper produced. Coal ia preferable for smelting to wood, 2 tons of coal doing as much as 3 tons of wood, and by the use of coal the most refractory ores could be reduced. And the report concludes with thi3 important sentence— " The value of all kinds of copper ore depends almost a3 much on their fusible as copper-bearing qualities, the latter two often occupying a too prominent place in determining their value." Tho above details are well worthy the attention of thoso who wish our new industry success.