NEVIS OIL SHALE

Otago Daily Times, Issue 24698, 29 August 1941, Page 4

NEVIS OIL SHALE

WORKING OF DEPOSIT •v" UNECONOMIC AT PRESENT FURTHER TESTS FLAW®) (0!c.) WELLINGTON. Aug. 28.. "A crucial point in the economic consideration of the .Nevis., .shale deposit is the average yield jpf oil per ton of shale,” said the. Mmister. of Mines, Mr P. C. Webb, in an interview to-day, when referring to the published remarks by Mr Joseph Stephens con- 1 cerning the comments in the Mines Statement on the Nevis shale deposits, “While it cannot be claimed that the sampling has been systematic and exhaustive,” Mr Webb Mid, samples collected both in T 922 and •Uus year indicate that the; vover-all grade is much too low in quality to be.considered economic at the present time. In 1922 four samples • were obtained at 10-foot intervals from an adit driven by Mr Graham, while this year one sarr.ple was obtained from 45 feet in this adit. Again, deep cuts were made in the surface outcrops in order to secure unweathered samples, while a weathered sample was chosen gar. ticularly for comparative purposes.- . Results of Analysis The Minister .pointed out that the assay yields of oil .were determined bv the Dominion Laboratory, .and that the Dominion analyst, had made it plain in his report that onlyabout 60 per cent, of these yields would be obtained when working on a commercial basts. This meant that the samples which assayed 20.6 and 14.3 gallons per ton would yield commercially approximately 12 and 8.5 gallons per ton re- , “It will be seen, therefore,” the Minister said, “that the samples so _ far obtained indicate very low grade shale indeed, and supportithe contention that there is no chance of making the deposit pay under present conditions. The Minister said that in .order to determine with a reasonable degree of accuracy the over-all grade of the, deposit it would be necessary to drill aid secure core samples from top to bottom. This would also serve to show whether or not there were any -richer : ■ layers in the deposit. Before the bore holes could be laid out to the best advantage. further geological work was required, and it was the intention, of the Government to carry out the work during the coming summer ’months.- ' Higher Values Necessary < ■': ;■ i The Minister said that the advah- : tages of cheap working conditions were fully appreciated; but it would be necessary to obtain consistently, .higher values than those secured hitherto before the deposit could be considered to have economic possibilities. As’far as / the quantify of shale available, was concerned, it had to be admitted that-it was impossible to make an.'accurate estimate without first carrying out a comprehensive and systematic drilling programme.’ V. « r: Ui According to the" geological•.-reports, the shale deposit at Nevis showed much evidence of contorting and faulting, and. that the beds were thrown into a series of small folds, Mr Webb concluded. If that structure was not given sufficient consideration, exaggerated estimates.'as to the quantity were likely to be made; \ ’ V* ,