Andrew. — On the Clarendon Phosphate-deposits. 481 



to be slowly converted by the action of humic and otter acids 

 before it is available for absorption. 



Prospects of the Industry. — The amount of rock-phosphate 

 occurring in the district cannot be accurately estimated at 

 present. As the original phosphate to which it owes its origin 

 was probably irregular in its distribution, so we must expect 

 our deposits of rock-phosphate to be irregularly distributed 

 along the outcrop of limestone. The question whether the 

 phosphate will occur between the already located outcrops can- 

 not at present receive a satisfactory answer ; in some places it 

 will, in others it will not ; the position of these respective places 

 can only be determined by further prospecting. From its 

 origin it follows that the phosphate will not extend inwards 

 under the protecting basalt cap ; and for this reason also it 

 follows that there is a greater chance of its occurring in quantity 

 under a gently sloping surface than under a steep one, for in 

 the former case a much greater width of limestone has been 

 exposed and subjected to the actions which lead to the formation 

 of the phosphate. Until prospecting affords more information 

 about the extension of the outcrops it would be useless to attempt 

 an estimate of the quantity in sight. 



The sale of the phosphate will, in my opinion, be confined 

 to New Zealand. To compete in foreign markets, high-grade 

 rock-phosphate must contain at least 77 per cent, of calcium- 

 phosphate — Ca 3 (P0 4 ) 2 — and its amount of alumina and iron 

 must be low. A reference to the list of analyses in this paper 

 will show that it will be difficult to guarantee that any large 

 quantity of the phosphate fulfils these requirements. Other 

 countries, moreover, owing to their more favourable geogra- 

 phical position, are better enabled to command the foreign 

 markets. In New Zealand the phosphate will have to com- 

 pete against the imported guanos, and against agricultural 

 limes produced by the burning of limestone ; against these it 

 is capable of holding its own, and of making progress. 



Other districts in New Zealand may also contain unrecognised 

 deposits of phosphate of lime. The discovery at Clarendon 

 was followed by the discovery of a smaller deposit at Enfield, 

 near Oamaru, but we have not heard much about this. Lime- 

 stone occurs in quantity throughout New Zealand, chiefly in 

 the South Island ; and its surface, especially where eroded to any 

 great extent, should be carefully examined for rock-phosphate. 

 The phosphate had been overlooked at Clarendon for many 

 years, and it may still be overlooked in some other locality. 

 It is easily mistaken for limestone, flint, &c, according to the 

 variety met with. It would be well worth while to submit to 

 qualitative chemical analysis any peculiar-looking rock-frag- 



16— Trans. 



