56 THE MINERALS OF TASMANIA. 



nearly all the ore is of a sulphide nature, so that this is a 

 somewhat unique occurrence in the mine." 



The analysis is as follows: — 



Per cent. 



Silica = 43-2 



Iron = 6-8 



Sulphur = 13-4 



Copper = 31-5 

 Not determined, but 



jirobably oxygen = 5-1 



100-0 



Assuming that the foreign matter merely consists of quartz 

 and iron pyrites, which is correct as far as we can see with 

 the naked eye, the specimen shows the following composi- 

 tion as a whole : — 



Per cent. 



Quartz = 43-2 



Iron pyrites ( Fe S,) = 14-59 



Covellite (Cu S) = 16-73 



Tenorite (Cu O) = 25-50 



100-02 



Taking into account only the mineral portion, the mixture 

 would seem to consist of — 



Per cent. 



Iron ).yrites (Fe S^) = 25-00 



Covellite (Cu S) = 30-00 



Tenorite (Cu O) = 45-00 



100-00 



The point of interest is that these decomposed and oxidised 

 products occur at such a low level in a sulphide mine. Of 

 course the occurance is very restricted. At the surface of 

 the North Lyell ore-bodies there is very little similar 

 material present, if any. 



94. Crocoisite (Chromate of Lead). 



No mineral discovery per se has accomplished so much 

 in advertising this State amongst mineralogists and those 

 interested in geological science as crocoisite. It is at once 

 one of the most beautiful in colouration as well as most 

 perfect in crystallographic growth that the world has pro- 



