BY L. A. COTTON. 825 



maline. Topaz and jasper are also to be found, and garnet is 

 invariably present where the gravels are diamond-bearing. An 

 iron -band, similar to that at Kirk's Hill and the Banca, was also 

 noted. The whole diamond-bearing area is some 300 yards in 

 length, and rather less than 100 yards in breadth. Its general 

 direction is south-west. The gravels rest on a granite-surface, 

 except at a spot near the centre of the area. Here, a small doler- 

 ite-neck, which is 60 yards long, by 10 to 15 yards wide, outcrops 

 at the surface. The diamonds recovered were largest and most 

 abundant in the vicinity of this neck. There are two shafts in the 

 neck; and the dolerite has been examined, but no diamonds have 

 been found in it. The deepest is 70 feet in depth, and the other 

 is 30 feet deep. The dolerite was soft and decomposed for a con- 

 siderable depth, but was hard and fairly fresh at the bottom of 

 the deep shaft. Gold was found in washing for the diamonds, but 

 only large flakes were recovered, as the method of diamond-wash- 

 ing could not save pieces less than 1-5 mm. in largest diameter. 

 About 10,000 carats of diamonds are reported to have been won 

 from this locality. 



V. Geology. 

 The geological features of the district include 

 (1)A series of clay-slates. 



(2) A series of granites. 



(3) Several basalt-flows. 



(4) A number of basic dykes. 



The clay-slates are the oldest rocks in this area. These have 

 been mentioned in a former paperO) on the district, and are not 

 important from the point of view of this publication. The granites 

 have been classified, in the same paper, into three types, the Acid 

 granite, the Tingha granite, and the Oakey Creek granite. The 

 granite which occurs at Copeton itself is intermediate in character 

 to the first and second types, and was included, in the paper 

 quoted, with the Tingha granite. A closer examination, however, 

 has indicated that it is perhaps better classed with the Acid type. 

 It is intermediate in chemical composition to the above types, re- 

 sembling the Acid type more in chemical composition, and the 

 Tingha type in physical characters. 

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