STEWART'S ISLAND TIN FIELDS.

Otago Witness, Issue 1950, 4 April 1889, Page 12

STEWART'S ISLAND TIN FIELDS.

! MR M'KAY'S REPORT. (Bt Our Own Cobbespondent.) Wellington, March 30. The preliminary report of Mr A. M'Eay, assistant geologist, on the tin deposits of Stewart's Island has just reached the Minister of Mines. A general description is given of the country in the vicinity of Port Pegasus, where the tin has hitherto been found, Mr M'Kay states that in the lower part of the valley gold was formerly found, bat not in payable quantity, and it proved particularly difficult to bsvo owing to the presence of what was supposed to be black sand, but which is now known to be " stream tin." The" wash" in the face of the old gold washings was only 12in or Win, and Mr M'Eay was told that a dishful of this wash only yielded about half an ounce of tin, so that unless the stuff could be rapidly turned over aud disposed of this ground would not pay for washing. Higher up on the eastern side of the middle basin the wash every* where appears too thin to pay unless it is much richer in tin than is reported to be the case. On the western side the wash is thicker, and on the Tasmanian claim it is said to be fully 6ft thick, yielding good prospects of tin. In some parts of the flat the wash is alleged to be 13f fe thick, but this is not yet proved. The upper basin was prospected without success. The east branch of Pegasus creek shows fairly good wash, 2ft to 4st thick, yielding fairly. Stream tin was also found at the survey camp to the south-west of the southern end of the "Tin Range," at an elevation of 570 ft above sea level. This is not in direct communication with the gravel in the neighbourhood of the creek, but seems part of the gravel stratum covering the greater part of the table land. The tin here is not associated with gravel sand, It is coarser in grain and a olean cample. The wash, however, is only a foot thick, and the prospects seldom exceed half an ounce of tin per dish. There was no time to make a full examination of the eastern side of the tic range, but the prospects were better along the South creek than Pegasus creek. Stream tin is widely distributed on the low ground and table land near Pegasus and South creeks ; but Mr s' Kay fears that the wash is too thin to pay for working. He admits that the general belief is otherwise, but he bases his views, on the relative values of tin and gold. The deposits of lode tin are confined to a a small area at the south end of the tin range, but he thinks that others may yet be found. As yet there is no information tending to prove that tin lodes exist in the granite which prevails there. The rocks constituting the tin range where alone tin ore has yet been found in situ are massive beds of quartzose and mica. These have been mistaken for true fissure reefs. Iron tungstate, which is apt to be -mistaken for tin, abounds in the range, but so far as Mr M'Eay could learn tin has been found only near the south end, and in only two places has any work been done towards proving the character of the supposed lode. The tin-bearing bed is a narrow rib of quartz in soft mica rock. There are three bands of quartz, but Mr M'Eay could only see tin or iron tungisfcate in one of them, which does not 'avetaga more than Sin, in thiokness, and' is often only an inch and a-half. . Eaatward'of .this, he saw an elUptlwl disconnected mW" of quarts 'parted from the rib and completely enclosed in mica

rook, and this gave the best specimens that lie saw anywhere in the' field. <An opening has been made in this only to' prooure specimens, and the work has been abandoned. Farther to the south-west three bands of quartz all carry tungsfcate and tin, and the middle one, which is the most productive in tin, has the thickness of 12m, Towards the eastern, end the" samples "are no richer than in the northern quarry, and it has been only because of the greater thickness of the quartz band that a greater bulk ot ore has been got here. The tin bearing ribs of quartz are mere eegrations in the mica. ' -\ As to the paying prospects Mr M'Kay s Bays" that more must be done before he can pronounce decidedly, but he is confident that tin ore will continue to ba found both to the dip and along the eastern side of the range from the southern quarry to the northern outcrop in Black's lease, and he sees no reason to think that tin is absent from the middle and northern parts of the tin range, or from the lower part of Pegasus creek on Toddand Harvey's freehold. From the considerable abundance, though perhaps not in paying quantities, and the wide distribution of stream tin along Pegasus creek and the east of the main watershed of the island, Mr M'Kay infers that other and richer deposits may yet be found in situ; and while he thinks that work should not 'be discontinued among the quartzose and mica rocks of the tin range, the granite and gneissic rocks to the eastward and westward should be carefully seaiehed, especially the felspar and quartz veins, which abound in more parts of the granite areas. It is reported that further and more promising finds of tin have been made at Stewart's Island, on the western side of the Bemarkables. The Tuapeka Times, commenting on Professor Black's return from Tasmania, says : — "We have seen in our own day men quite as sanguine as the Professor, and every bit as audacious in, cracking up a mine, look very' small when it came to the time for paying out the dividends. And judging by the signs in the atmosphere, we are much inclined to think that this kind of thing will continue until a few of the boom promoters are handed over to the frenzied and disappointed shareholders to be' dealt with as they list." A chemist in Canterbury having applied to a gentleman in Dunedin for a sample of the ore from Pegasus to enable him to test it, a fair average sample was sent, not by any means one of the richest specimens, and he has now sent the following report, and a " stick " of tin aboat 3in long with a smaller piece, both extracted from the ore. He says : " I have much pleasure in forwarding to you by to-day's post, under separate cover, the results of our assay of the ore sent by you. I have only tested the piece of tin ore as yet, which has yielded very good results as you will see, and is a very pure sample. The large piece you sent me weighed before being broken up just 15oz, and yielded OOOgr of ore, which on being smelted gave me 540gr of pure tin, which is equal to 56 per cent, of the quantity of ore treated. I may state that the stone was chiefly composed of sandstone and contained a very large quantity of mica, whioh was very troublesome to get rid of, and entailed a slight loss of ore when washed. The stream tin I have not treated yet as there is suoh a small quantity of it. . . I believe there is a grand payable investment in it if it will yield all round like the sample you seat to me. . . My friend says he never saw a sample equal to this that I am sending you from any of the mines in Tasmania." The tin can be seen at our office. It will be noted that the percentage of 56 per cent, is on the washed ore, the percentage on the whole stone is 7| per cent, or at the rate of 1681bs of pure tin to the ton of stone.