NELSON GOVERNMENT GAZETTE.

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not to their own eruption. This mass of serpentinous rock is traversed by dykes of true plutonic rocks, some of which do not even yet reach the surface except in the beds of the streams; the north-west flank rests on a dyke of porphyritic diorite, which is distinct in mineral character from the Dun Mountain metamorphic series. With regard to the time at which the metamorphism of the Dun Mountain group took place, except in a general way that it was subsequent to the Nianic period, we have no direct means of determining, nor yet as to the amount of denudation which has taken place since such metamorphism was effected; these questions can only be solved when an accurate survey of the whole district is accomplished.

Nelson has several times been flattered with delusive promises of great mineral wealth in "The Dun Mountain," and even in the face of past experience, many still hold to the opinion that at some time large deposits of copper and chrome ore will be discovered in the immediate vicinity of the old trials; I am afraid I can hold out no such hopes. After carefully examining the whole of the old workings, and entering all that I possibly could, I was convinced that any mining researches in that locality would prove futile, ending only in disappointment and loss.

It is a well known fact that native copper, chalcopyrite, fahluz, and malachite have been found in the serpentine, on the south-east side of the Wooded Peak (now called Big Twin), and also in Windtrap Gully; these were accompanied by silicates of copper, both dioptare and cryscolla, which, from their bright blue and green colors, make a great display, even when in very small quantities. These silicates may be traced from one trial working to another in a straight line (of course allowing for the rise and fall of the surface) along the side of the hill, as far as the junction of the south branch of the Maitai and the Windtrap Gully, a distance of nearly two miles; but this must not be construed into an indication that any important quantity of ore exists in the serpentine. I found this line to be parallel to the course of an elvan dyke (one of those before mentioned as not reaching the surface), which is found in Roding River, and also in the Maitai; in both these places the water has cut through 12 or 14 feet from its top. The annexed sketch shows how completely the serpentine covers it, also the flat top of the dyke; the elvanite is cleaved in flatish wedge-shaped layers, and in the Maitai is slightly bent over to the south; this cleavage is evidently due to great pressure after cooling, and it is a legitimate inference that the same cause would produce a line of fracture in the serpentine, especially if contraction were the motive power, when the serpentine would break over the hard unyielding elvan.

In hard compact rocks this would have formed a fissure, and perhaps ultimately a mineral vein, but not so in serpentine, which gives way in a multitude of small cracks and joints, through a given width; in this case it is 4 or 5 feet; these cracks would then become the outlet for water which might find its way up from below, and if this water held copper or iron salts in solution it would inevitably deposit some or all on the serpentine in exceedingly thin films, and as the stone would break at these places it would be almost impossible to tell its real value until analysed. The fact that the water from the serpentine does hold copper in solution is proved by the floor and stones in one of the old drives being thickly coated with silicate of copper, also by the water from another drive producing all the symptoms of metallic poisoning on both myself and assistant. I am fully convinced that there is a deposit of copper ore somewhere in the district, but the serpentine so completely obliterates all indications of its locality, that it is difficult to come to any conclusion; the only way to search for it is either to go right away from the serpentine, or else to take advantage of the natural cuttings formed by the rivers, to get as near to the base of the serpentine and olivine formation as possible. The place I should choose for a trial would be a point in the Roding River bearing S. 50° W. from Coad's Mine, where a gossan may be seen running parallel to and in contact with a hard porphyritic dyke, which presents the same appearance as that previously mentioned; the course is N. and S., dip 88° E.; but, instead of driving towards the Wooded Peak, a southerly direction ought to be taken, so that if possible the point where this dyke intersects another, which occurs about three-quarters of a mile farther up the stream, might be reached. It is true that there are no superficial indications in this direction; but I have before shown that they are valueless in serpentine, and therefore their absence is of no consequence, especially as the presumptive evidence is good. From the tenor of the foregoing remarks it will be apparent that I do not consider that the property of the Dun Mountain Company would pay for further explorations; a few pieces of ore might and probably would be found, but there could be no certainty about it. I do not know of any copper lodes in serpentine which are really worth working, for, although immense returns may be obtained one month, many years may elapse before any farther profit is made.

CHROME.

All the chrome workings having fallen in and the men who worked in them dispersed, I could not get any very definite information respecting the manner in which the chrome occurred; it appears however to have been between the serpentine and hornblend rock when of first-rate quality, the commoner being in the serpentine; there is a little still left about the outcrops of the old workings; but I was assured by the present manager to the Company that there was none left underground. The way that both this and the copper occur is very common on the outskirts of a mineral country, and may be taken as a good indication that mineral wealth does exist in the Province, probably near the junction of the true igneous rocks and the palaeozoic slates.

GOLD.

Until the analysis of the various rocks are completed it is premature to express any decided opinion on the prospect of payable goldreefs being found in the immediate neighborhood of Nelson, but, judging from lithological characters and structure, the Roding River rocks are strictly analogous to the auriferous ones of Gympie Creek, specimens of which were presented to the Colonial Museum by Mr. T. R. Hackett. In a report furnished to the Queensland Government, Mr. Hackett, in speaking of the auriferous belt, says,†

†Geological and Mining Report on the Gympie Creek Goldfields, 1869.