348 Proceedings of tlie Roi/al Society of Victoria. 



In No. 5 tunnel, east end, dyke material now kaolinised rami- 

 fies throuffh the siliceous ore as under : — 



<; - - 



-3 (d. - 



> 



Of still greater interest than the sulphide ore and the skeleton 

 ore, from which the sulphides have been removed, is the 

 secondary ore. It is of most unusual character, and the writer 

 has not met with anything similar elsewhere. The distinction 

 between this ore and the cellular, siliceous ore surrounding it 

 appears not to have been sufficiently emphasised, and this has 

 probably led to some confusion. In the earlier stages of the 

 mine the relation of this ore to its surroundings was obscure, 

 but the further operations that resulted in the removal of the 

 whole of it, and also of the plug of sandstone in its centre by 

 open cast workings, disclosed these relations in a very distinct 

 manner. 



Roughly, the secondary ore of Mt. Morgan was funnel-shaped. 

 It was surrounded at the surface by the cellular siliceous ore 

 on the north and west sides, and by kaolinised igneous rock 

 on the south and east sides. In outline it was of irregular 

 oval form and covered, with the plug of sandstone in its centre, 

 aia area of about 2^ acres on the top of the Mount. The ex- 

 treme summit of the Mount was just west of the edge of this 

 area. Everywhere this ore covered the cellular siliceous ore, and 

 to a depth of 50 or 60 feet, but extended to a depth of 160 feet 



