BY LliO A. COTTON. ' 507 



is worthy of note that the widest portious of the lode are usually 

 the richest. 



The shoot previously mentioned, and represented in text-fig. 2, 

 is wider than the normal vein. The latest developmental work 

 in the mine was carried out in prospecting this shoot. Moore's 

 shaft was sunk 150 feet below the main drive, and a winze- 

 (marked C in text-fig.2) was put down to the same level, from a 

 spot some distance north, in the main drive. From the bottom 

 of each of these, drives were started to connect with one another. 

 A very interesting and important phenomenon was observed in 

 the drive from the bottom of the winze. After driving for a 

 short distance, it was found that water was entering the drive 

 underfoot. A further examination revealed the fact that the 

 water was proceeding from the clay-selvage. After this, the 

 drive was observed to become hot and stuffy, as well as being 

 continually wet. Unfortunately the tempei-ature of this rising 

 water was not recorded, but the Manager is of the opinion that 

 it was appreciably warm, and that the heat was due to this 

 cause. The foul air was probably due to gases emanating from 

 the water. The amount of water entering the drive was esti- 

 mated at about 4,000 gallons per day. This drive was under 

 water at the time of my visit. The drive from Moore's shaft did 

 not meet with any such phenomena, and remained cool and fresh 

 throughout. 



Another interesting feature in this part of the mine is the 

 abundant replacement of crystallised quartz by zinc-blende. This 

 process has been most active at the spot marked B in text-fig. 2. 

 It will be seen that this is close to the place where the water 

 was observed entering the mine from underfoot. The signifi- 

 cance of this will be pointed out later. 



Three phases in the replacement are well marked : — 



The first con.sists of masses of crystallised quartz in which an 

 occasional crystal of quartz has been partially or wholly replaced^ 

 by zinc-blende. In this phase, the cry.stals adjoining the replaced- 

 crystal are unafi'ected by the process(Plate xv. fig. 2, A). 



