CLARENDON PHOSPHATE DEPOSITS

Otago Daily Times, Issue 26463, 17 May 1947, Page 2

CLARENDON PHOSPHATE DEPOSITS

REPORT ON INVESTIGATIONS In a report on the investigations of the Clarendon phosphate deposits issued by the Department of Scientific and Industrial Research, Mr R. W. Willett, of the office of geological survey, Wellington,, reaches some interesting conclusions. The indicated quantity of available medium-grade phosphate, he says, is between 28.000 and 60,000 cubic yards. The quantity is too small to be of more than some value during an emergency restricting overseas supplies of rock phosphate. The fact that the quantities at Clarendon are not confined to one block, but occur as several separate blocks, tends to reduce the economic value. Under any conditions, the medium-grade phosphate cannot be regarded as other than an inconsiderable addition to the supply from overseas. The investigation heavily underlines the dependence of New Zealand on overseas sources of natural phosphate. Mr Willett adds. The indicated quantity of available low-grade phosphate lies between 76,000 and 150.000 cubic yards. It is spread over several fairly widelyscattered blocks, a fact that must be considered when discusisng its availability. The total quantity of available lowgrade phosphate is sufficient to satisfy the present demand for a cheap low-phosphate-content fertiliser for about three or four years. The quantity is insufficient to warrant any process of beneficiation to produce a higher-grade commercial product. The friable Clarendon sand cannot be regarded as a reserve of phosphate within the present definition of a reserve, Mr Willett concludes. It contains insufficient phophate to justify further beneficiation experiments under present technical practice. In the future, as beneficiation processes advance and overseas resources dwindle, the Clarendon sand may come to be regarded as a phosphate reserve. Produced Results The interest to farmers of this report is increased by the fact that a number of them in recent years used phosphate from Clarendon—often called Kapiti phosphate after one of the blocks from which it was got—and in both Otago and Southland some surprising results were obtained with it. Farmers had to supply their own bags and pay transport costs themselves. Many were a little sceptical about its value and used it only because they could obtain nothing that might be considered better. They reasoned that a heavy application of it to their soil would be necessary, and it was frequently applied at the rate of half a ton an acre. It obviously “ had something ” to contribute to deficient soils, this being proved by the production results achieved in certain areas. What that “something” was has never been determined.