BY L. A. COTTON. 



erysts of felspar and quartz. The felspars normally show signs of 

 corrosion, and may be subangular or even ellipsoidal. A large 

 inclusion, showing corroded 

 felspars, is represented in 

 Plate xc, fig.l. 



It is of interest to note 

 that inclusions of an identi- 

 cal nature exist in the Acid 

 o;ranite at the Dutchman 

 tin-lode, near Torington. 

 This is about 70 miles to 

 the north-east of the Cope- 

 ton occurrence. As no such 

 inclusions have been found 

 in the Tingha granite, it is 

 probable that the Oakey 

 Creek granite is more closely 

 related to the Acid granite 

 than to this more basic type. 

 As its morphological affini- 

 ties, however, are more re- 

 lated to those of the Tingha 

 granite, it is probably inter- 

 mediate to these two types. 



Dykes. — A number of 

 felsite-dykes occur in the 

 Copeton area, and these 

 intersect both the Oakey 

 Creek and Acid granites. 

 None of these have yet been 

 proved to be diamond-bear- 

 ing, but some of them occur 

 in positions which suggest 

 that they may, at least, be 



Scale. 

 200 



Text-fig. 4. — Plan of the dolerite-dyke at 

 Oakey Creek showing the spot (marked 

 by a circle) where the diamond was 

 found in matrix. 



regarded as possible sources of diamond-supply. In addition to 

 these, there are two intrusions of dolerite known in the Oakey 

 Creek granite, and both of these are undoubtedly intimately asso- 



