XXX11. ABSTRACT OF PROCEEDINGS. 



orogenic movements, but instead they appear to be arranged near 

 the foci of volcanic eruptions. 



Wolfram, molybdenite and bismuth in Australia are associated 

 with siliceous granites, the tin-wolfram types being character- 

 istically more siliceous than the molybdenite types. Siliceous 

 granite appears to be the original host of the minerals, and the 

 deposits are most frequently arranged within the granites near 

 their intrusive contacts with other rocks, and they occur as 'pipes,' 

 'veins,' or 'segregations,' but whereas the tin and wolfram fre- 

 quently leave their host and form deposits in the associated sedi- 

 ments, the molybdenite very rarely forsakes the original granite 

 host. 



In Western Australia the tin and molybdenite is of Pre-Cam_ 

 brian age, and is almost negligible commercially. Similarly for 

 Central Australia. In Tasmania these minerals appear to belong 

 to the close of the Devonian, so also the Victorian and New South 

 Wales areas south of the Hunter zone of weakness. North and 

 east of this zone the tin, wolfram, molybdenite and bismuth 

 deposits belong probably to the close of the Palaeozoic. Tin occurs 

 in large amounts in Tasmania, New South Wales, and Queensland, 

 while molybdenite is hardly known in West Australia, it occurs 

 as an ancient deposit in South Australia, but not as yet proved 

 to be commercial. In Tasmania it becomes a little more abund- 

 ant. In New South Wales south of the Hunter depression it is 

 much more abundant, increasingly so in New England, and also 

 in Northern Queensland. The group has not been recorded except 

 as mineral curiosities from New Zealand. 



A study of these fold movements and mineral regions might be 

 expected to throw considerable light on the real geological relations 

 which may exist between New Guinea, New Caledonia, and New 

 Zealand on the one hand, and Australasia on the other. Discussion 

 of such relations, however, is beyond the scope of this brief note. 



Messrs. O. A. Sussmilch and W.G. Stone gave an account 

 of their work in connection with the geology of the Jenolan 

 Caves area, which is published in extenso in this Journal, 

 pp. 332 - 384. 



