BY H. C. RICHARDS. 205 



The alunogen deposit considered above is distant 

 about 16 miles from the nearest potash-rich volcanic rocks, 

 and this, coupled with the mode of origin put forward by 

 the writer, renders the possibility of finding aliuiite in the 

 area quite unfavourable. If the alunogen had occurred as 

 a product of sublimation in a volcanic vent, as does some- 

 times happen, then the conditions might have been 

 favoiirable. 



The a]kali-rieh trachytes in the immediate vicinity 

 of Springsure were examined by the author but nothing at 

 all suggestive of an alunite dejiosit was noted. 



There are undoubtedly many 'tons of the incrustation 

 available but it is difficult to form any reliable estimate 

 as to the quantity owdng to the varying thickness of the 

 deposit and the uneven surface of the cave and cliff. The 

 formation of the material is still going on as evidenced by 

 the recoating of scraped sandstone surfaces and the coating 

 of the hornet nests in the cave. 



TJie fact, that the broken up sandstone forms a coating 

 of this material comparatively rapidl}^ on exposure, suggests 

 that after the main incrustation has been removed the sand- 

 stone could be broken down, crushed, and spread out evenly 

 on trays. If the rain were kept off by some light covering 

 and the crushed sandstone sprayed from time to time Mith 

 a dilute solution of sulphuric acid no doubt the development 

 of the incrustation would be accelerated. If the surface of 

 the sandstone were smooth the coating might be scraped 

 off, the sandstone raked up thoroughly and treated again 

 until exhausted sufficiently when the sandstone could be 

 renewed. 



The question of whether it would jiaj' to treat the sand- 

 stone in some such manner depends of course on the amount 

 of aluminium sulphate in the sandstone and the cost of 

 treatment, which would be mainty that of labour. The 

 quantity of sandstone available is very large and, if necessary, 

 sufficient material is available to be worked on a large 

 scale. The sandstone would probably become less and less 

 rich as one receded from the face in a horizontal direction, 

 and what would happen on descending vertically is very 

 difficult to conjecture. 



