N.Z. URANIUM DEPOSITS

Press, Volume XCVI, Issue 28420, 29 October 1957, Page 8

N.Z. URANIUM DEPOSITS

Colorado Rock’s Similarity

"The Press" Special Service DUNEDIN, October 28.

The New Zealand deposits of uraniferous and possible uraniumbearing rocks are strikingly similar to those of the Colorado Plateau in the United States, but unfortunately are only a fraction of the area, according to Professor G. J. Williams, dean of the faculty of mines and metallurgy at the University of Otago. He was giving a presidential address to the Otago branch of the New Zealand Geographical Society.

In both countries the uranium occurred as coffinite—hydrous uranium silicate—and was bedded in sedimentary rocks in seams, rather than reefs. Small amounts of iron pyrites were also present in both deposits. These close analogies with the United States fields would help any developments in this country, because techniques already worked out m America could be used in ’ New Zealand. The known uranium deposits in New Zealand all occurred in the Hawks Crag breccia, which was scattered throughout the South Island. There were 125 square miles of this rock, and although a few more miles might be accessible by underground mining there was an overlay of other rocks. Occurrence of Rock The breccia was present in the Taieri Gorge area and at Naseby in Central Otago. Both these area.i had been tested, but with negative results. It also occurred in South Westland and this area had yet to be explored. Besides the original discovery in the Buller Gorge, uranium was present at the mouth of the Fox River and at Bullock Creek on the West Coast. Areas of breccia at Slaty and Pike creeks and on the Waitahu river, near Reefton. would be explored in the near future. Professor Williams said.

Looking for the mineral, however. was perhaps the easiest part. The question was whether it was worth working. It would be quite uneconomic to begin mining unless 750 tons of uranium oxide could be produced each year.

The usual method of extraction was to crush the rock and to use sulphuric acid to extract the uranium, but that might not be economic here. Professor Williams said, because so much acid would be wasted through the presence of carbonate also in the rock. Almost certainly an alkali process of extraction would have to be used and. although that had lower capital costs, working costs were higher.