Vol. 69.] PETKOXOGY OF THE KALGOOBLIE GOLDEIELD. 



633 



Mr. E. S. Simpson have described a series of andesites capping 

 one of the hills. They are stated to be vesicular, amygdaloidal, 

 sometimes showing flow-structure and sometimes brecciated. 1 

 Some confusion of very different rocks has evidently taken place ; 

 G.S.M. 6973, Creme d'Or G.M.L. 389, is a very fresh igneous rock : 

 from the published analysis it would seem to be a basalt rather than 

 an andesite, and in all probability it is a comparatively recent dyke- 

 rock ; the other specimens which I have seen (G.S.M. 74 & 7307, 

 Cue Hill ; 3823, New Princess Extended G.M., Cue) are fine-grained 

 zoisite-amphibolites, considerably contact-altered, and sometimes 

 brecciated and recemented by a coarse matrix of hornblende and 

 zoisite. An analysis of one of them is quoted below. 



Other localities where the fine-grained amphibolites have been 

 recognized may be briefly cited : — Cumberland G.M., Norseman ; 

 Laverton (G.S.M. 6537) ; Lennonville (G.S.M. 3966) ; Mount 

 Malcolm (G.S.M. 4425) ; and Kimberley (G.S.M. 3749). 



No analyses from Kalgoorlie are available, but there are two of 

 similar rocks from other goldfields, which agree closely enough with 

 the analysis of the Ovifak basalt. 





I. II. III. 



SiO.j 



TiO, 



48-10 

 041 



15-41 



10-32 

 4-33 

 0-05 

 6-38 



12-73 

 2-11 

 0-14 

 033 

 0-04 



012 

 0-25 



48-06 

 090 



16-21 

 0-89 



10-37 



48-04 

 039 



13-13 

 6-89 



11-14 



AI0O3 



F&A 



FeO 



MnO 



MgO 



0-59 0-11 

 6-67 S-T7 



CaO 



Na.O 



KoO 



11-37 

 2-50 

 0-27 

 0-59 



o-io 



tr. 

 1-03 

 0-34 



10-87 

 2-83 

 0-06 



0-07 



0-98 

 0-79 

 025 



tr. 



H 2 + 



H 2 0- 



P»0 5 



CO? . 



FeSo .. 



S 



C 



H(?) 



CI 



Totals 



100-72 



99-89 



100-72 



311 



C. C. Williams. 



3-04 



E. S. Simpson. 



2-958 







I. Fine-grained ampliibolite. G.S.M. 3823, Cue 



No. 29 (1907) pt. 2, p. 53. 

 II. Fine-Drained ampliibolite. G.S.M. 4425. 

 Goldfield. Ibid. No. 11 (1903) p. 7. 

 III. Basalt. Ovifak, Disko (Greenland). 

 Gesteinslehre ' 3rd ed. (1910) p. 399. 



Bull. Geol. Surv. W. Austral. 

 Mount Malcolm, Mount Margaret 

 H. Rosenbusch, ' Elemente der 



Bull. Geol. Surv. W. Austral. No. 29 (1907) pt. 1, pp. 17-18; pt. 

 pp. 9, 44, 46, 52, & 53. 



