[Proc. Roy. Soc. Victoria, 28 (N.S.), Part I., 1915]. 



Akt. VI. — Notes on an Occurrence of Quartz in Basalt. 



By CHARLES FENNER, B.Sc. 

 (School of Mines, Ballarat). 



(Communicated by Professor E. W. Skeats). 



[Read June 10th, 1915]. 



I.— Introductory. 



My attention was first directed towards occurrences of quartz in 

 basalt by noting, some four years ago, the abundance of angular 

 quartz fragments that are to be found over the basaltic plains which 

 stretch to the southward from Mt. Greenock, a volcanic hill in 

 Central Victoria. 



Following this up, it was found that at a spot on McCallum's 

 Creek, where the stream has cut through to the Ordovician bedrock, 

 the cliffs on the left bank showed a remarkable exposure of quartz 

 in the basalt. Since then, the occurrence of quartz, sparsely, in our 

 basalts has been found so common, that attention has been given, 

 as far as the literature was accessible, to similar or related occur- 

 rences in other parts of the world. While results in the Mt. Greenock 

 area are somewhat disappointing, they are certainly not without 

 interest. 



II.— Description of the Mt. Greenock area. 



As will be seen by the small sketch map (Fig. 1), copied from 

 that published by the Geological Survey of Victoria, the geology of 

 the area is simple. East and west of the basalt flow, low timbered 

 ordovician ranges occur; the ordovician slates are traversed by 

 innumerable quartz veins. 



The deep lead gravels which were buried by the basalt were wide, 

 and, in places, up to 30 feet thick; the basalt sheet averaged about 

 100 feet in thickness. The eastern drainage is now carried off by 

 McCallum's Creek to the Loddon River, and the eastern edge of 

 the basalt lias been much more vigorously dissected than the western. 

 The buried gravels were highly auriferous, and have been exten- 

 sively mined for practically their full length. 



