222 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



In New South Wales there are two principal diamond districts (Fig. 43). One 



stretch of country extending to the north-west of Sydney, as far as the Cudgegong 



iver, and to the west of Sydney, as far as the Lachlan river. The other diamond 



IS a 

 riv 



Fig. 43. Diamond-fields of New South Wales. (Scale, 1 : 10,000,000.) 



district is in the north-east corner of the State, in the district of the Gwydir river, a 

 tributary of the Darling ; it embraces the neighbourbood of Inverel] and Bingera, and 

 extends to the east of these townships into New England. In these districts the diamond 

 occurs in sands together with gold and tin-stone (cassiterite), and with one possible exception 

 it has never been found in the solid rock ; it is therefore impossible to make any suggestion 

 as to the nature of the rock in which the diamond was formed. 



In the southern diamond districts the diamond-bearing debris is mainly confined to 

 ancient water-courses of Pliocene (a subdivision of Tertiary) age. When the precious stone 

 is found in the beds of recent rivers and streams, it is always associated with material derived 

 from these older deposits, which has been redeposited by natural agencies or during the 

 process of gold-washing, &c. In this district the diamond is invariably accompanied by gold 



