17

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In this company's mine a considerable quantity of calcite (and also some aragonite) is met with. It was found that with the process of dry crushing only 40 per cent, of the bullion could be extracted, the reason assigned being that where the calcite was associated with the ore the burning set free the C0 2 from the calcite, thus producing lime, and this, amalgamating with the clayey matter, formed a strong cement sufficient to bind the ore to some extent, and so prevent the free penetration and action of the cyanide solution. Wet crushing has been adopted m the main, there being a plant of forty heads of 1,050 lb. stamps and twenty-nine cyanide-vats at Waitekauri, and a small plant (ten heads) for dry crushing and cyaniding at the mine. Karangahake is now an important part of "the Upper Thames Mining District. During the year considerable developments have been effected at the New Zealand Grown, the Woodstock, and the New Zealand Talisman and Talisman Extended Mines. These two latter are now amalgamated under the title of " The Talisman Consolidated (Limited)," and the system of dry crushing hitherto in vogue is being superseded by that of wet crushing, a battery of "forty stamps, with amalgamating, concentrating, and cyanide plants, being in course of erection at my visit. At the Crown Mine, Karangahake, recent improvements consist in the sinking of a new underlay shaft on the reef, and opening out on the latter, which is of considerable width (often attaining 20ft.), and lies at an angle of about 45°. The ore has a value of about £2 7s. per ton. Hoisting and pumping machinery have been erected at this shaft, the power being compressed air, generated near the mouth of the mine by a two-stage compressor, built on the Eeidler system by Messrs. Eraser and Chalmers. Compressed air is also used for working rock-drills in the mine. The compressor is worked by a 10 ft. diameter Pelton wheel, under a pressure of water due to a head of 80 ft., or, say, 34 lb. per square inch. Improvements in the plant connected with the Woodstock Company's battery have been effected during the year, also a shaft for the purpose of winning the reefs at deeper levels has been started. Other mining operations on a small scale are conducted in the locality. I understand recent discoveries at the Imperial Mine are of a satisfactory character, and that it is intended to erect machinery to treat the ore. At Waiorongomai, near Te Aroha, Mr. E. H. Hardy is working the Empire and New Find Nos. 1 and 2. The reef worked is nearly vertical, its course being a little east of north and west of south. The ground is hard and costly to work, and only a portion of the reef is extracted— viz., a band of about 4 ft. wide near the middle, the value of which is about £2 ss. per ton. The battery comprises a small but very complete plant, consisting of ten stamps, six berdans, one Watson and Denny and one Fraser amalgamating-pans, one Union vanner, one Whlfiey concentrator, and cyanide appliances. At the Thames mining matters have been very quiet during a good portion of the year. Much interest was taken, and considerable expectation centred, in the pumping and sinking operations at the Thames-Hauraki Company's shaft, but owing to financial considerations the work here was suspended. Owing to this the question as to the existence of payable ground at deeper levels than have yet been reached is still unsettled. The circumstance is greatly regretted, and especially so in face of the fact that a very substantial subsidy has already been paid by the Government as a contribution towards the erection of heavy pumping machinery, and the prospecting of the ground at depth (by sinking), with a view to the further development of this part of the goldfield. Mines in the immediate neighbourhood—viz., the May Queen (Hauraki), Moanataiari, Waiotahi, Kuranui-Caledonian, Fame and Fortune, New Whau, as well as those at Tapu Creek, Waiomo Creek, Tararu Creek, &c, were visited. They are fully reported on by Mr. Coutts, Inspector of Mines. I cannot say I was very favourably impressed with the prospects of mining in the locality as regards the future, unless ground of a remunerative character is found at greater depth. In the interests of the industry, and of the district generally, it appears most desirable that the sinking of the Thames-Hauraki shaft should be resumed as quickly as possible, and carried down to a depth which will, once and for all time, settle the question as to the existence or otherwise of payable reefs below the line at which operations have hitherto stopped, and which forms the top of what has been described as " an unproductive zone." At Coromandel mining matters are also very dull. It is well known that much of the ground in this locality is patchy, gold being found in pockets of considerable richness rather than in general distribution through the quartz. Owing to this feature narrow leaders and stringers have been worked on to a considerable extent, and quality (specimen stone) rather than quantity (general quartz) sought after. Near the township the Hauraki, Golden Pah, Hauraki Main Lode, Bunker's Hill, Blagrove's Freehold, Kapanga, Scotty's, Hauraki, and Success Mines were all working at my visit. On inspection of the underground workings of several mines I found that the prospects of some of them were not of an encouraging character so far as the ground had been proved. Since then at least four of the mines named have suspended operations, but it is quite possible that under a scheme of amalgamation and concentration of operations some of them may be again worked. The Hauraki Freehold Gold-mining Company have a considerable area of freehold property on which comparatively little work has as yet been done, and this will afford a good field for prospecting. The old Welcome Find shaft has been reopened for the purpose of affording facilities for the development of the field. Taken as a whole this company's ground appears to present the greatest local potentialities. At Tokatea and in the neighbourhood of Kennedy Bay prospects appear fairly good. The Royal Oak of Hauraki Mine, Tokatea, has been put under new management, and I understand that developments of a somewhat comprehensive character are being undertaken. The Four-in-hand Mine, near Kennedy Bay, has been successful, and gives promise of a good future. The stone is yielding a return of, approximately, £4 15s. per ton. 3—C. 3.