226 REV. J. MILNE CURKAN. 



that an apparent fiuidal structure may be developed in a rock 

 which has never actually been in a fluid or plastic condition. 



Slice 142. — Quartzite, Belarbigil Station, Talbragar River, New 

 South Wales. In very many parts of these Colonies, basalts are 

 found overlying Tertiary drifts. Sometimes these drifts have been 

 altered to quartzites by the basalts. The present slide is a fair 

 sample of the rock produced in this way. Under the microscope 

 the quartz is seen preserving its original outlines, but in the 

 cementing material, probably a finely granular quartz and fels- 

 pathic sand, a good deal of secondary quartz has been developed 

 Quartzites produced in this way are common in the three Colonies 

 of which the Writer has a knowledge, New South Wales, Victoria 

 and Queensland. 



There is a general impression that most of our rich gold deposits 

 are connected with dioritic rocks. As a rule, this view may hold 

 good, but my experience has taught me that very many of the 

 so-called diorites are really more augitic than hornblendic in com- 

 position. As examples of this, I might refer to many slices that 

 accompany this paper. Slices 102 and 103 are very fair examples 

 of diabase rocks, in which no hornblende is present but that have 

 been considered diorites. The rocks already described from 

 Blayney, and Carcoar, are also examples of rocks into whose 

 composition no hornblende enters, but which in hand specimens, 

 undoubtedly resemble diorites. Some intrusive rocks from 

 Gulgong and Parkes, New South Wales (See Slices 121, 122, 119) 

 are certainly not typical diorites, although without a detailed 

 examination in the field, it would be unwise to say that we may not 

 have intrusive masses of augitic rocks, altered locally to diorites. 



Slice 151. — Diorite from thirteen miles south of Dubbo. This 

 is a good example of a holo-crystalline plagioclase hornblende rock. 

 The rock is intrusive in granite, and in character very closely 

 approaches the typical diorite. 



Slice 155. — Porphyritic Diorite, from Bogan River, twenty 

 miles above Nyngan, New South Wales. In hand-specimens this 



