Art. XVI. — The Petrology of certain Victorian Granites. 



By EVELYN G. HOGG, M.A., 



Acting Professor of Mathematics, University of Tasmania. 



[Read before the Australasian Association for the Advancement of 

 Science, Melbourne, 12th January, 1900.] 



The principal sources of information with respect to the distri- 

 bution of granite in Victoria are the essay of Mr. A. R. C. Selwyn, 

 published in connection with the catalogue of the Victorian 

 Exhibition of 1866; and the text-book on the Geology and 

 Physical Geography of Victoria of Mr. R. A. F, Murray, pub- 

 lished in 1887. Brief macroscopic descriptions of Victorian 

 granites may be found in the " Catalogue of the Rock and 

 Mineral specimens in the Technological Museum, Melbourne," 

 edited by the late J. Cosmo Newbery. 



Up to the present time little attention appears to have been 

 paid to the petrology of the granites of Victoria. Notes on the 

 subject are scattered through the writings of Mr. A. W. Howitt, 

 and an interesting paper on the granite of Cape Woollomai, by 

 Mr. James {Stirling, Government Geologist, occurs in the Progress 

 Report of the Mines Department, 1899, vol. x., p. 107. 



The author of the present paper has had during the past few 

 years many ojDportunities of collecting granites in Victoria, and 

 he has recently received from Mr. A. E. Kitson, F.G.S., of the 

 Mines Department, through the courtesy of Mr. Stirling, a few 

 specimens of granitic rocks from some of the more inaccessible 

 parts of Victoria. 



In the following paper the petrological characters of these 

 granites are briefly described : — The terminology of rocks of 

 granitic type is a matter of discussion. In the present paper 

 normal granite is defined as a holocrystalline rock composed of 

 quartz, biotite and two felspars, the triclinic felspar being sub- 

 sidiary to the monoclinic. Variation from the normal form may, 

 among other ways, take place by a change in tlie relative propor- 



