MICROSCOPIC STRUCTURE OF SOME AUSTRALIAN ROCKS. 179 



A CONTRIBUTION TO THE MICROSCOPIC STRUCTURE 

 OF SOME AUSTRALIAN ROCKS. 



By Rev. J. Milne Curran, f.g.s. 

 [With Plates xx. - xxn.] 



[Read before the Royal Society, N.S. Wales, August 5, 1891.'] 



Contents. 

 I . — Introduction . 

 II. — Methods of Eesearch. 

 III. — Previous observers. 

 IV. — Notable structures referred to. 

 V. — Classification. 

 VI. — Description of Slices. 

 VII. — Conclusion. 

 VIII.— Index. 



Introduction. 

 Some five years ago, I had exceptional facilities to collect 

 Australian Rocks from many widely separated localities. As 

 opportunities offered, I sliced the more interesting of these samples 

 for microscopical examination. At one time the material accu- 

 mulated to some five hundred micro-slices. It would obviously be 

 impractical to deal with this amount of material in one paper. I 

 have therefore, selected one hundred and sixty slides for descrip- 

 tion, as a contribution to Australian Microscopic Petrography. 



In making this list, I have been guided by three considerations. 

 Firstly, I have, selected those rocks for description which I had 

 previously studied in the field, and, therefore, with the geological 

 relations of which I am familiar. In the second place, I am 

 anxious to bring new matter before the Royal Society. Finally, 

 I have given preference to those intrusive rocks that prevail on 

 well-tried gold-fields, or are associated with any form of mineral 

 wealth, particularly in this colony. Even within the limits, I 

 shall be able to point to nearly every leading form of eruptive 



