43 



The country-rock at Yalwal is a highly-altered slate (5642), Case 58. 

 and the gold appears to be contained principally by narrow 

 ferruginous veins traversing it. In case 136, near the door, 

 will be found a very line block admirably showing the nature of 

 the Talwal ore. The slate is traversed by a network of quartz 

 which is fringed by narrow gold-bearing veins. One such vein 

 goes right across the specimen. 9462 in this case is similar. 



At Grrassy Gully, only 8 miles from Yalwal, the ore is of an 

 entirely different and very extraordinary character. Microscopic 

 examination has shown that it is an ancient lava flow, the rock 

 rliyolite, highly altered during the course of geological ages. The 

 gold occurs right through the stone in a very fine state of 

 division (9175, and others). This Grassy Gully ore is closely 

 analogous to that from Pambula shown in the same case (see 

 page 44). 



8985, Moruya Gold and Silver Mine : solid arsenical pyrites, 

 assaying 15 dwt. gold and 10 oz. of silver per ton. 



The Mount Dromedary Mine is of considerable interest. 

 Mount Dromedary is a mass of granite rising up through the 

 surrounding slate. The granite is traversed by very narrow 

 veins of pyrites, which are sometimes rich in gold. The pyrites 

 is associatedwith small quantities of chalybite, sulphide of bismuth, 

 &e. 8582 shows a little acicular black bismuth ore. 8853 has 

 been cut and polished to show the brecciation often present : 

 it will be noted that the pyrites occurs in angular fragments. 

 The pyrites is in a very unstable form, decomposing so rapidly 

 that specimens are most diflScult to preserve. At Wagonga 

 Heads there is a dyke of gold-bearing felsite (8385). 



Wolumla, Yambulla. — 6410, Auriferous pyromorphite,* from 

 near Wyndham. 



At "VVolumla the country rock is granite, and the ore itself is 

 in part impregnated granite. 7348, Wolumla, rotten granitic 

 rock showing gold. 



* Page 41 for other instances of this. 



