PLATINUM IN AFRICA

Evening Star, Issue 18999, 22 July 1925, Page 4

PLATINUM IN AFRICA

TRANSVAAL DISCOVERIES Africa’s claim to be the land of 'surprises has, perhaps, never received more emphatic endorsement than from the recent discoveries of platinum in the Transvaal province of the Union of Smith Africa, (writes the Cape Town correspondent of the ‘Argus,’ April 9). Not since the discovery of stanniferous pipes and lenses in the Bushvcld, to the north-east and north-west of Pretoria, twenty years ami, has any mineral discovery in the Transvaal engaged so much interest as has the finding of platinum in the Waterberg district during the past year or so, and in the Lydcnburg area during recent months. Within the past few weeks the metal has also been found in the Bustenburg, Middolburg, and Potgiotersrust districts, and it is becoming increasingly evident that a very large portion of the Central Transvaal is potentially, at least, platinum-bearing. The discoveries have led to extraordinary scenes on the Johannesburg and other local stock exchanges. For instance, the shares of the Transvaal Consolidated Land and Exploration Company, which possesses millions of acres of land, much of it in the platiniferous areas, and upon some of which rich platinum deposits have been found, have jumped from 10s, at which they stood towards the end of last year, to 70s, at which business is being done at present. There are over forty companies already formed to work areas which they have acquired on the lines of strike, and in nearly every case the capital required—and the amounts asked for range , from £IOO,OOO down to £s,ooo—has been easily obtained, and, in the case of properties where development work has been done and good values obtained, the shares have been largely over-subscribed. The 5s shares of'’these undertakings have soared, and in several cases now stand at 755; in two instances they are unobtainable at offers of 90s. The first discoveries were made in the Watcrberg district, where an unpromis-ing-looking quartz lode—so unpromising, in fact, as to have been deemed unworthy of examination by the scorns of prospectors who during the past thirty years must, have kicked their feet against it—has been found in places, at any rate, to be extremely rich in platinum. In the western part of the Lydcnburg district economically important concentrations of platinum have been found on two widely-sopurtcd horizons in the norite zone of the Bushvcld. Igneous complexthe lower of dunile horizon—has the metal as a primary constituent of a remarkable iron-rich dunitc, composed essentially of the variety of olivine known as hortonolite. On "the upper, or main, horizon, platinum occurs as a constituent of a dark-colored, pyroxene-rich, pseudopor.phyritic, diallage norite, often merging into felspathic pyroxenite, which originally contained small amounts of copper and iron pyrites. The writer has only just returned from investigating the Watcrberg and Lydenburg platinum occurrences, having been specially commissioned for that purpose. These two districts were selected as having been the earlier to lie discovers, and consequently much more development work had been done. In his investigations the writer had the advantage of being furnished with the results of the minute investigations already made by the foremost authorities upon geology and mining in .South Africa, among them being several consulting engineers to gold mining companies; of Dr Percy A. Wagner, of the Government geological survey; Dr Hans Mcrcnsky, and Dr E. I. Mellor (consulting geologists), Messrs C. £>. Kingston, J, E. Mills Davies (consulting engineers), the prospecting and assaying staffs of several large corporation.', and of local managers of mines, ole. Before giving particulars of what iho writer found, it may first be stated that the oe- J currencc in the Watcrberg -and I.ydenhurg districts have each beta maced for scores of miles, the ou'uops often running without a break for miles. Generally speaking, platinum values in- the Watcrberg district are very erratic, but give an excellent paying average. In the Lydcnburg district values do not soar so high, but are more even. If anything, the Lydcnburg district seems likely to develop into the most important field, and, in fact, many mining authorities already visualise tfic town of Lydcnburg as the centre of a “ Platinum Hand,” which will attain such importance its to he ready to till the gap when the time comes that tho “ Gold Hand ” is wonted out.

’The first mine opened on the 'Watcrberg field is situated on the site of the first discovery of platinum. Values in this mine fluctuate enormously over small sections, and in order to keep a close check on (lie platiniferous content in development, two samples are taken for each 2lt, while approximately 1,400 assays are made each month. At' some points phenomenally rich values have been determined, and assays going as high as 3,ooodwt to the ton have been obtained. The value of the ore available at the lime of the visit in ’payable ore dumps was about 5.000 tons, plus a further substantial tonnage in the mine. Some considerable stretches have been exploited with wonderful results; for instance, at the 50ft level a.value of 199dwt per ton over 63in for a distance of 40ft have been determined and at another point 43dwt over 66in over a somewhat longer “ ran ” of ore. The profitable lode width is substantial, and this, combined with the facts that good values continue to be secured in depth, that there is no apparent change in mineralisation as shaft and winzes aro pushed down, and that values, though essentially erratic, can be so controlled that highly "payable tonnages of substantial quality are available, has placed tho mine in a satisfactory position. It lias now been opened up to a depth of 150 ft, and good stretches of ore have been located on the 50ft and 100 ft levels. Two vortical shafts are being sunk to 500 ft, A smalt plant is at work, but already the company has a larger plant coming forward to treat 1,000 tons a mouth. Exhaustive tests have determined the ability of a simple crushing and concentration plant, embodying classifiers and Wilfle.y and Seimpan tables, to _ extract 60 per cent, of the ore content. Chlorination will then be employed, and a total extraction of about 92 per cent, can be anticipated. The whole of tho costs will bo covered by of the metal to the. ton of ore. 'The new plant will bo in operation towards the end of the current year,'and the output from this _ will represent tho first marketing of platinum on a commercial scale by the Union of South Africa.

Turning to (lie Lydenhurg field, tho ■writer Ims selected a mine situated on file farm, Onverwacht, in dnnite formation, where a sample taken from outcrop gave a value of 53d wt of platinum per ton. The outcropping portion of tho platinum-bearing lock occupies the entire surface over a continuous area, measuring roughly 60ft by 60ft. The full extent and form of the ore body remains to be determined. When the writer was there a vertical shaft had readied a depth of 44ft, the bottom of the shaft being still in the same formation The shaft was carefully sampled in 12in sections. The average" value to 40ft was 9.Brhvt of platinum per ton. the average value for the last 10ft being IS.Odwt, Since that time the shaft has reached a depth of 70ft without change in the formation. Tim average value, from 40ft to 50ft is 20.5dwt per ton, and from 50ft to 60ft 27.4dwt. Tho assays of the samples taken between 60ft depth and 70ft have not yet been received. Tho writer wishes to make it plain that the results at this mine are well above the average of the field. Results at a mine on the same field, which is below the, average, are as follow: A vertical shaft sunk 130 ft struck the reef at 22ft. Samples over the upper portion gave the following assay values:— South side of shaft, 3.Bdwt over 48in; north side of shaft, 4.47dwf over 48in; east side of shaft, 4.4dwt over 60in. Two adit cuttings are being driven to connect with the shaft, ami have reached a length of 40ft. Results obtained are as follow; Adit No. 1 at 15ft, 2.Bsdwt oyer 54in j

at 30ft, 4.ldwt, over 54in. Adit No. 2, at 20ft, 4.45dwt, over 64in; at 30ft, 4.9dwt, over 54in. Individual lenses to the number of seven have been exposed on the lenticular ore bodies underlying the reef trenching. They invariably carry high values, ranging from s.9dwt to 11.6dwt.

While there is not tho slightest doubt that both these fields (Watevberg and Lydcnburg) will bo large producers of platinum within a short time, it must bo emphasised that people should not invest money in any concern until they have obtained full particulars about them. Many of the companies now floated have, as their only inducement to investors, tho fact that they arc on the same formation as that in which good platinum values have been found by other companies. There are bare patches of very large extent. Even with regard to other mines, whore tiie results of propecting are higmy encouraging, it must be emphasised, also, that, in the’majority of cases, much more work must ba done and much more time must elapse before any reliable estimates can be made as to the property being payable on any considerable scale.