50 



MiNERALOGIGAL NOTES iFROM THE LABORATORY 



OF THE Wallaroo Smelting Works. 



By T. C. Cloud, Assoc. Eoy. School of Mines, F.C.S., F.I.C., 

 CoiT. Meinb. 



[Read September 6, 1881.] 



In tlie course of my labours in connection with the prepara- 

 tion of a catalogue of South Australian minerals, I have found 

 it necessary to submit certain specimens to a chemical exami- 

 nation, and in some instances to make a complete quantitative 

 analysis. T have also in the course of my duties in the 

 Laboratory of the Wallaroo vSmelting AVorks been called upon 

 from time to time to analyse minerals found in this colony and 

 from other localities. As it will be some time yet before the 

 catalogue of South Australian minerals is ready, I have thought 

 it would not be uninteresting to the fellows of the Eoyal 

 Society if the following notes were submitted at the present 

 time. And I may be allowed to express the hope that by so 

 doing I may obtain further assistance and matter for the 

 catalogue, ^o particular order will be followed in these notes, 

 but I shall select them as they occur in my note-book. One of 

 the first South Australian minerals, which I had occasion to 

 examine was 



Atacamite. 

 This mineral is known to occur in three states of hydration 

 containing in round numbers 12, 17, and 22 per cent, of water. 

 I incline to the opinion that two if not all of these varieties 

 occur in this colony ; indeed, I believe I have them all in my 

 collection, but want of time and opportunity has prevented me 

 from establishing this fact for certain. As an example, how- 

 ever, of the first-named variety, I may instance the atacamite 

 which occurs frequently in the mines on Yorke's Peninsula, 

 and whicli was represented by unique specimens from the New 

 Cornwall Mine. The form generally assumed by the mineral 

 in this locality is that of the combination of the rhombic prism 

 with the pyramid. In some instances the prism is very short 

 or is entirely wanting, and it becomes difficult to distinguish 

 the pyramid from an octahedron. The specimen employed for 



