COPPER AT MOKE CREEK.

THE following Report from Mr. Hector to Dr. Hector, is published for general information.

THOMAS DICK,
Provincial Secretary
Dunedin,
25th Jan., 1864.

Queenstown,
14th Jan., 1864.

SIR,—In pursuance to your Instructions I have examined the Copper Lode in Moke Creek, both in regard to its geological position as well as respecting the facilities it presents for mining, and have the honor to report to you the data connected with it, and the conclusions I have drawn.

The Lode crosses the valley about the middle of Moke Creek, about half a mile above the point where bridle track from Queenstown reaches the Creek. It is exposed on the north side in the precipitous rock, 60ft. in height, where it averages 1½ft. in width. On the south side of the stream there is a considerable land-slip, which entirely covers up the Lode; but in the slipped masses of rock and earth the best stones of ore are found, one of those I saw weighing 50 lbs. and containing probably 12 per cent. of copper.

The Lode is composed of mundic, quartz, and copper ore. Its run is N. 40° W., being apparently the same as that of strata (but as so short a length of the lode was exposed, its run can hardly be ascertained with exactness). The underlay of the lode is 15° west, the dip of the strata being 50° west: it therefore dips at a considerable angle to that of the strata.

The prevailing rock, for two miles both to the east and west of the lode, is a thinly foliated blue micacious ripple schist (of which I send samples), but immediately on the sides of the lode, and forming its walls, there is a different rock, viz., on the east side and forming its foot wall are 3 feet of thinly foliated shale, with iron pyrites or “mundic” in the foliations (specimens No. 1467); further east is a greenish, chloritic, hard rock, which splits into obliquely angled pieces (No. 1469); past which is the said ripple schist.

On the west or hanging wall of the lode is 10 ft. of soft, blue shale, thinly laminated and slightly corrugated (No. 1475), this shale containing in some places the oxides of copper and iron in the cross fracture (No. 1473). Further west is a greenish rock, with large patches of black slate, say 15ft. in thickness, adjoining which further west is the before-mentioned ripple schist, which characterises the auriferous part of Moke Creek. This, in some places near the lode, also contains iron pyrites in the foliations (No. 1464).

The fact of the dip of the lode being at an angle to that of the strata, and that of the rock adjoining the two “walls” of the lode being different from the adjoining strata, clearly prove that this a true lode, and not a mere contemporaneous vein.

The facilities for working the lode on either side of the valley are considerable, as the hill rises on both sides at a considerable angle and to a great height; so that “adits” driven on the lode into the hill above the flood lines of the creek would develop the lode to a great depth from the surface at a very small expense. These “Adit” levels should be driven first, which with the necessary “air shafts” (which) would at once prove the lode.

Unless richer ore were met with in driving the adit on the course of the lode, the only way of working the mine to a profit would be to smelt the ore on the spot, or rather on the borders of the Lake, where fuel and “flux” could be obtained; the average of the ore at present exposed, not being sufficiently rich to be worth conveying to England, without being previously reduced to a “regulus.”

The average produce of the ore I saw, not being above 10 per cent., on account of the great quantity of “mundic” or iron pyrites which is intimately mixed with the greater portion of it.

This would not be worth above £9 per ton in England; but by one smelting process (with a previous inexpensive calcination in the open air), the ore could be reduced to a regulus of 70 to 75 per cent. worth at the present rate of copper (£98) £56 to £71 per ton. The ore could be smelted by either charcoal or wood, which is abundant on the borders of the Lake.

Smelting works capable of reducing 1000 tons of ore per month would cost about £2000.

A road would also be required from the mine to the Wakatipu Lake, which, however, presents no difficulty, as at the head of the Moke Creek there are two passes, one leading to the “Seven-mile Rush,” and the other leading to Fuze Creek, or the “Twelve-mile Rush.” The road through the former pass is about six and a-half miles long, and the watershed to be passed over, at a distance of two and a-half miles from the Lake, does not exceed 600 feet in height. Ascending from the mine, the gradient of the road would be about 100 feet in the mile, and descending to the Lake about 400 feet to the mile, which considering that laden drays would only go in this one direction, would by no means be a steep incline. The most expensive part of the road would be the first two miles from the mine, where there will be some very difficult side cuttings. On the other portions, there will be but occasional side cuttings where the ground is not very steep. The point where the hill rises most abruptly from the valley, viz., about two miles from the mine, the ground shows an inclination by the clinometer of 40 degrees, but this is an exception, although the hills are certainly rather abrupt in this portion of the road. Against this, there are terraces of considerable height, where no outlay is required.

The expense of making a dray road twelve feet wide, from the lode to the Seven-mile rush, I estimate at £800. A tramway might, however, be preferable.

There is splendid grass land around the Moke Lake, where the horses required for the transport of the ore would find excellent pasture.

On the Moke Lake is timber of the description necessary for the purpose of the mine, and in sufficient quantity.

No copper mine having yet been worked in this older formation, in this island, no such decided opinion can be given as could be formed on a copper lode in the fully explored formations in Europe, but my own impression is, from the 20 years’ experience I have had in copper mining in various countries in Europe, that this lode is fully worthy of a trial, and that the expenditure of capital in driving levels would be quite justified; the local facilities for working the lode being quite sufficient to compensate for its distance from the seaport. Should, by this expenditure, the lode prove as productive as I expect, the further expenditure for roadmaking and for the erection of smelting works, could then be undertaken.

I have the honor to be,

Sir,
Your most obedient servant,

T. R. HACKET.

Dr. Hector,
Provincial Geologist.