ORIGIN AND MODE OF OCCURRENCE OF GOLD-BEARING VEINS. 139 



11 about twelve in number, and nearly parallel. Their course is 

 " nearly north and south, with a dip to the eastward, and they 

 "occupy a width of from 80 to 120 feet in the aggregate." 



The conglomerate Mr. Pitman describes as consisting of quartz 

 and feldspar crystals in a blue silico-feldspathic matrix, with 

 indistinct outlines of large pebbles of slate and sandstone. 



At Adelong, also, there are found what are called "ore channels" 

 by the miner. These are narrow belts occurring in the country 

 rock, like large lodes, and consisting of a kind of chlorite schist. 

 Quartz occurs in these places either as lenticular masses or more 

 or less irregular veins, sometimes adhering to the walls of the 

 channel or belt, and at others in some other part of it. The 

 mines have been worked to a depth of 1050 feet. This mode of 

 occurrence of quartz vein is very similar to that described by Mr. 

 Pitman at Hill End, and it seems to be a characteristic mode of 

 occurrence of auriferous lodes in different parts of the colony 

 (vide Section of Three Ore Channels at Hill End, Fig. 29). 



The following description by Mr. C. S. Wilkinson, F.G.S., 

 F.L.S., Government Geologist for the Colony, of a mode of 

 occurrence of quartz veins upon the Wentworth gold-field is most 

 interesting. He says as follows : — 



"The reefs occur at the junction of the serpentine and 

 "hornblendic feldsite, the latter in places passing into diorite. 

 "Along this line of junction is what the miners term the 'lode,' 

 "which at the surface is a fissure, six feet or more in width, 

 "extending in direction S. 50° E. (or nearly south-east and 

 " north-west) for a distance of 50 chains. It is filled with a red 

 " sandy ferruginous clay, containing hard siliceous accretions of 

 "irregular shape, locally termed 'clinker.' This lode dips to the 

 " north-east at an angle of about 65° though in some places it is 

 "nearly vertical. The hornblendic feldsite forms the foot- wall and 

 "serpentine the hanging wall. In the feldsite, at varying 

 " distances along the lode, are quartz veins from a few inches to 

 "six feet thick, coming in from the west and abutting against the 

 " lode, which they appear to follow down and form irregular quartz 

 " pipes or shoots dipping diagonally along the lode towards the 

 " east. The veins have only been found to contain payable gold 

 "where they occur in the lode and form the shoots." 



Another lode that is interesting in its mode of occurrence is the 

 Marshall McMahon reef, at Watson's Creek, near Murrumburrah, 

 on the Southern Railway line, between Sydney and Melbourne, 

 and about 230 miles from the former place. This vein is situated 

 in granite, and was very rich in its upper levels, but has become 

 so heavily charged with iron pyrites in its lower levels that the 

 machinery necessary is of a very different kind to that used in 

 the first instance, such machinery is, however, being now erected,. 



