and their Contact Zones. 79 



These examples may serve to illustrate the reefs of this 

 district, with the exception of one at Lower Swift's Creek, 

 formerly known as the Caroline, and now as the Duke of 

 Cornwall. This reef is at a distance from the contact, in 

 the nodular argillaceous schists and quartz schists which 

 fringe the area of regional metamorphism. 



I note the following as to this reef: — This quartz vein 

 runs east and west, and thus forms an exception to the 

 general rule at Swift's Creek. It crosses a spur from the 

 range on the north side of the stream, and adits have been 

 driven from both sides. Most work has, however, been 

 done at the eastern end of the lode. 



There are two parallel veins distant a few yards apart 

 The veins vary in width. The quartz is somewhat glassy and 

 crystalline. Pyrites is less frequent here than is the case 

 in many other reefs of the district, and the gold is rather 

 generally diffused in small particles than found in any 

 denned " shoot." At the western end of the lode No. 1 

 adit was driven for 150 feet in the northern vein, the width 

 of the quartz being about 22 inches, and having an under- 

 lay of about 80° north. Stone from this adit crushed from 

 6 — 8 dwt. per ton. The cap only of the southern vein at the 

 western end was opened up, but a shaft was then sunk to 

 50 feet, the quartz being about 40 inches wide, and 15 tons 

 of stone taken from this place gave at the rate of 8 dwts. 

 8 grs. per ton. 



At the eastern end an adit has been driven for some 

 200 feet along the course of the lode, and the vein stoped 

 out to the surface. 



Returns given in the quarterly reports of Mining Sur- 

 veyors and Registrars, published by the Department of 

 Mines, show that the stone from these adits yielded at the 

 rate of 11 dwts. per ton. 



The mine is now idle. This vein has as yet never been 

 thoroughly tested. It may probably extend to greater 

 depths than any other of the reefs opened at Swift's Creek. 



The quartz reefs of Swift's Creek may be classed as (1) 

 those situated in the line of contact between the intrusive 

 masses and the sediments, and (2) those situated in the 

 regionally metamorphosed Silurian beyond the contact. I 

 have shown that the former penetrate through the contact 

 into the underlying quartz diorites; that they have been found 

 to be richest near the surface, to dwindle away as they 

 penetrate deeper, and to become less auriferous, or cease at 



