BY LEO A. COTTON. 767 



consists of a number of small quartz-veins, more or less parallel 

 to one another. These vary in thickness, from a mere crack up 

 to 2 inches in width. Most of the veins are about J of an inch 

 wide, but there is a main vein, about '2 inches thick, which has 

 <ietermined the course of the workings. The small quartz-veins 

 are very irregular, and pinch out abruptly. In constitution 

 they vary from solid quartz to solid cassiterite. Where these 

 veins are oblique to the direction of the trench, they may be seen 

 prominently marking the sides, but are evidently too far-.spaced 

 and patchy for economic working. Most of the veins are sharply 

 marked off from the granite, which is hard and undecomposed. 

 No trace of greisen is present. 



A prominent feature of this deposit is the number of iron- 

 stained bands accompanying many of the veins. The veins are 

 evidently of the nature of impregnations from the vein-fissure, 

 at some stage in its formation. They occur sometimes on one 

 side only, and sometimes on both sides of tlie quartz. The zone 

 of iron-stained granite is usually wider than the quartz-vein. 

 There are three phases of occurrence — 



(i ) Iron-stained bands with neither quartz nor cassiterite. 



(ii.) Iron-stained bands with central veins of quartz. These often 

 contain cassiterite at the junction of the quartz and iron-stained 

 granite. 



(iii.) Iron-stained bands with central veins of cassiterite. 



A section of the lode, as seen at the end of the open cut, is 

 given in text-fig. 3. 



Class vi. — Quartz- Felspar . 



This type is economically the most important, because not only 

 are these deposits usually the richest, but are also the most easily 

 mined. The association of the quartz and felspar is as follows: — 



(i.) Veins of highly felspathic rock traversed by veins of trans- 

 lucent quartz. 



(ii.) Quartz and felspar intimately intergrown. 



(i.) A typical example of the tirst, is a reef about ^ of a mile 

 to the east of Sutherland's Water, about a mile from its junction 



