NEVIS DEPOSITS OF SHALE

Dominion, Volume 34, Issue 287, 1 September 1941, Page 5

NEVIS DEPOSITS OF SHALE

Minister’s Statement INVESTIGATIONS TO BE MADE It must be admitted that it was impossible to make an accurate estimate of the quantity of shale available in the Nevis deposits without first carrying out a comprehensive and systematic drilling programme, said the Minister of Mines, Mr. Webb, replying to comments by Mr. J. Stephens on the Mines Statement.

The Minister said that according to the geological reports, the shale deposit at Nevis showed much evidence of contorting and faulting, and the beds were thrown into, a series of small folds. If this structure was not given sufficient consideration, exaggerated estimates as to quantity were likely to be made. . ' \ The crucial point in the economic consideration of the Nevis shale deposit was the average yield of oil a ton of shale. Though it could be claimed that the sampling had been systematic and exhaustive, the various samples collected both in 1922 and this year indicated an overall grade much too low in quality to be considered economic at present. In 1922 four samples were obtained at 10ft. intervals from an adit driven by Mrl Graham, and this year one sample was obtained from -15 ft. in this adit. Again, deep cuts were made in surface outcrops to secure unweathered samples, a weathered sample being chosen particularly for comparative purposes. Assay Yields.

The Minister said that the assay’ yields of oil as determined by the Dominion Laboratory were made by the Gray King Carbonization Assay (000 degrees Centigrade), and that the Dominion Analyst had made it plain in his report that only about 00 per cent, of these yields would be obtained when working on a commercial basts. This meant that the samples which assayed 20.0 and 14.3 gallons a ton would yield commercially, approximately 12 and .5.5 gallons a ton respectively. It would be seen, therefore, that the samples so far obtained indicated a very low grade shale indeed, and supported the contention that there was t.o chance of making the deposit pay under present conditions. Tlte Minister said that to determine with a reasonable degree of accuracy the overall grade of the deposit, it would be necessary to drill and secure core samples from top to bottom. This would also serve to show whether there were any richer layers in the, deposit. Before bore holes could be laid out to best advantage, further geological work was required and it was the intention of the Government to carry out tlte work during the coming summer months.

Tlte Minister said that (lie advantages 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.